{"id":8505,"date":"2025-10-07T13:33:40","date_gmt":"2025-10-07T13:33:40","guid":{"rendered":"https:\/\/pokecon.jp\/job\/?p=8505"},"modified":"2025-10-07T13:33:40","modified_gmt":"2025-10-07T13:33:40","slug":"go%e3%81%ae%e7%b5%84%e3%81%bf%e8%be%bc%e3%81%bf%e9%96%a2%e6%95%b0-len-%e3%81%ab%e8%a9%b3%e3%81%97%e3%81%8f%e3%81%aa%e3%82%8b-every-tech-blog","status":"publish","type":"post","link":"https:\/\/pokecon.jp\/job\/8505\/","title":{"rendered":"Go\u306e\u7d44\u307f\u8fbc\u307f\u95a2\u6570 len() \u306b\u8a73\u3057\u304f\u306a\u308b &#8211; every Tech Blog"},"content":{"rendered":"\n<\/p>\n<div>\n<p><figure class=\"figure-image figure-image-fotolife\" title=\"title\"><span itemscope=\"\" itemtype=\"http:\/\/schema.org\/Photograph\"><img decoding=\"async\" src=\"https:\/\/cdn-ak.f.st-hatena.com\/images\/fotolife\/M\/Motoshi0711\/20251007\/20251007192921.png\" alt=\"Go\u306e\u7d44\u307f\u8fbc\u307f\u95a2\u6570 len() \u306b\u8a73\u3057\u304f\u306a\u308b\" width=\"960\" height=\"540\" loading=\"lazy\" title=\"\" class=\"hatena-fotolife\" itemprop=\"image\"\/><\/span><figcaption>title<\/figcaption><\/figure>\n<\/p>\n<h2 id=\"\u306f\u3058\u3081\u306b\">\u306f\u3058\u3081\u306b<\/h2>\n<p>\u3053\u3093\u306b\u3061\u306f\u3002\u30c7\u30ea\u30c3\u30b7\u30e5\u30ad\u30c3\u30c1\u30f3\u958b\u767a\u90e8\u3067\u30d0\u30c3\u30af\u30a8\u30f3\u30c9\u30a8\u30f3\u30b8\u30cb\u30a2\u3092\u3057\u3066\u3044\u308b\u9234\u6728\u3067\u3059\u3002<\/p>\n<p>Go\u8a00\u8a9e\u306e\u7d44\u307f\u8fbc\u307f\u95a2\u6570<code>len()<\/code>\u306f\u3001\u4e00\u898b\u30b7\u30f3\u30d7\u30eb\u306b\u914d\u5217\u3084\u30b9\u30e9\u30a4\u30b9\u306a\u3069\u306e\u300c\u9577\u3055\u300d\u3092\u8fd4\u3059\u95a2\u6570\u3067\u3059\u304c\u3001\u305d\u306e\u5b9f\u88c5\u306f\u30b3\u30f3\u30d1\u30a4\u30e9\u3084\u30e9\u30f3\u30bf\u30a4\u30e0\u30ec\u30d9\u30eb\u3067\u7279\u5225\u306a\u6271\u3044\u3092\u53d7\u3051\u3066\u3044\u307e\u3059\u3002\u672c\u8a18\u4e8b\u3067\u306f\u3001<code>len<\/code>\u306e\u8a00\u8a9e\u4ed5\u69d8\u304b\u3089\u30b3\u30f3\u30d1\u30a4\u30e9\u5185\u90e8\u306e\u51e6\u7406\u30d5\u30ed\u30fc\u3001SSA\u6700\u9069\u5316\u3001\u6700\u7d42\u7684\u306a\u30a2\u30bb\u30f3\u30d6\u30ea\u30b3\u30fc\u30c9\u3001\u3055\u3089\u306b\u306fruntime\u5185\u90e8\u69cb\u9020\u4f53\u306b\u81f3\u308b\u307e\u3067\u3092\u7db2\u7f85\u7684\u306b\u9806\u3092\u8ffd\u3063\u3066\u8a73\u3057\u304f\u8aac\u660e\u3057\u3066\u3044\u304d\u307e\u3059\u3002<\/p>\n<h2 id=\"len\u306e\u4ed5\u69d8\u3068\u5b9a\u6570\u8a55\u4fa1\"><code>len<\/code>\u306e\u4ed5\u69d8\u3068\u5b9a\u6570\u8a55\u4fa1<\/h2>\n<p>\u307e\u305a\u3001Go\u8a00\u8a9e\u4ed5\u69d8\u306b\u304a\u3044\u3066<code>len(x)<\/code>\u304c\u3069\u306e\u3088\u3046\u306b\u5b9a\u7fa9\u3055\u308c\u3066\u3044\u308b\u304b\u3092\u78ba\u8a8d\u3057\u307e\u3057\u3087\u3046\u3002<code>len<\/code>\u306f\u7d44\u307f\u8fbc\u307f\u95a2\u6570\u3067\u3042\u308a\u3001\u4ee5\u4e0b\u306e\u3088\u3046\u306a\u69d8\u3005\u306a\u578b\u306b\u9069\u7528\u3067\u304d\u307e\u3059\u3002<\/p>\n<ul>\n<li><strong>\u6587\u5b57\u5217 (<code>string<\/code>)<\/strong>: \u30d0\u30a4\u30c8\u6570\uff08\u6587\u5b57\u5217\u306e\u9577\u3055\uff09\u3092\u8fd4\u3059<\/li>\n<li><strong>\u914d\u5217 (<code>[n]T<\/code> \u307e\u305f\u306f\u30dd\u30a4\u30f3\u30bf <code>*[n]T<\/code>)<\/strong>: \u914d\u5217\u306e\u8981\u7d20\u6570\u3092\u8fd4\u3059\uff08\u56fa\u5b9a\u9577n\u3002\u30dd\u30a4\u30f3\u30bf\u7d4c\u7531\u3067\u3082\u914d\u5217\u9577\u306f\u578b\u3067\u6c7a\u307e\u308b\uff09<\/li>\n<li><strong>\u30b9\u30e9\u30a4\u30b9 (<code>[]T<\/code>)<\/strong>: \u30b9\u30e9\u30a4\u30b9\u306e\u73fe\u5728\u306e\u9577\u3055\uff08\u8981\u7d20\u6570\uff09\u3092\u8fd4\u3059<\/li>\n<li><strong>\u30de\u30c3\u30d7 (<code>map[K]T<\/code>)<\/strong>: \u30de\u30c3\u30d7\u306b\u5b9a\u7fa9\u3055\u308c\u3066\u3044\u308b\u30ad\u30fc\u306e\u6570\u3092\u8fd4\u3059<\/li>\n<li><strong>\u30c1\u30e3\u30cd\u30eb (<code>chan T<\/code>)<\/strong>: \u30c1\u30e3\u30cd\u30eb\u306e\u30d0\u30c3\u30d5\u30a1\u306b\u84c4\u7a4d\u3055\u308c\u3066\u3044\u308b\u8981\u7d20\u6570\u3092\u8fd4\u3059<\/li>\n<\/ul>\n<p>\u3044\u305a\u308c\u306e\u5834\u5408\u3082<code>len(x)<\/code>\u306e\u8fd4\u308a\u5024\u306e\u578b\u306f<code>int<\/code>\u3067\u3042\u308a\u3001\u305d\u306e\u5024\u306f\u5fc5\u305a<code>int<\/code>\u578b\u306b\u53ce\u307e\u308a\u307e\u3059\u3002\u307e\u305f\u3001<strong><code>nil<\/code>\u306e\u30b9\u30e9\u30a4\u30b9\u30fb\u30de\u30c3\u30d7\u30fb\u30c1\u30e3\u30cd\u30eb\u306b\u5bfe\u3059\u308b\u9577\u3055\u306f\u5e38\u306b0<\/strong>\u306b\u306a\u308b\u3053\u3068\u304c\u660e\u793a\u3055\u308c\u3066\u3044\u307e\u3059\u3002<\/p>\n<p>\u3055\u3089\u306b<code>len<\/code>\u306f\u5834\u5408\u306b\u3088\u3063\u3066<strong>\u30b3\u30f3\u30d1\u30a4\u30eb\u6642\u5b9a\u6570<\/strong>\u3068\u3057\u3066\u8a55\u4fa1\u3055\u308c\u307e\u3059\u3002\u5177\u4f53\u7684\u306b\u306f\u3001<\/p>\n<ul>\n<li>\u5f15\u6570\u304c<strong>\u6587\u5b57\u5217\u30ea\u30c6\u30e9\u30eb<\/strong>\u306e\u5834\u5408\u3001<code>len<\/code>\u306e\u7d50\u679c\u306f\u30b3\u30f3\u30d1\u30a4\u30eb\u6642\u5b9a\u6570\u306b\u306a\u308a\u307e\u3059\uff08\u6587\u5b57\u5217\u306e\u30d0\u30a4\u30c8\u6570\u3092\u305d\u306e\u307e\u307e\u5b9a\u6570\u3068\u3057\u3066\u6271\u3046\uff09\u3002<\/li>\n<li>\u5f15\u6570\u306e\u578b\u304c<strong>\u914d\u5217\u578b<\/strong>\uff08\u307e\u305f\u306f\u914d\u5217\u3078\u306e\u30dd\u30a4\u30f3\u30bf\u578b\uff09\u3067\u3001\u305d\u306e\u5f15\u6570\u306e\u5f0f\u306b\u30c1\u30e3\u30cd\u30eb\u53d7\u4fe1\u3084\u975e\u5b9a\u6570\u95a2\u6570\u547c\u3073\u51fa\u3057\u3092\u542b\u307e\u306a\u3044\u5834\u5408\u3001<code>len<\/code>\u3068<code>cap<\/code>\u306e\u7d50\u679c\u306f\u5b9a\u6570\u3068\u307f\u306a\u3055\u308c\u307e\u3059\u3002\u3053\u306e\u5834\u5408\u3001\u305d\u306e\u914d\u5217\u5f0f\u81ea\u4f53\u306f\u5b9f\u884c\u6642\u306b\u8a55\u4fa1\u3055\u308c\u307e\u305b\u3093\u3002\u8a00\u3044\u63db\u3048\u308c\u3070\u3001\u914d\u5217\u9577\u304c\u30b3\u30f3\u30d1\u30a4\u30eb\u6642\u306b\u5224\u660e\u3057\u3066\u3044\u3066\u526f\u4f5c\u7528\u3082\u306a\u3044\u3068\u304d\u3001\u30b3\u30f3\u30d1\u30a4\u30e9\u306f<code>len<\/code>\u3092\u5358\u306a\u308b\u5b9a\u6570\u3068\u3057\u3066\u51e6\u7406\u3057\u307e\u3059\u3002<\/li>\n<\/ul>\n<blockquote>\n<p><strong>\u4f8b<\/strong><br \/>\n\u4ee5\u4e0b\u306e\u3088\u3046\u306b\u3001\u9577\u3055\u304c\u6c7a\u307e\u3063\u3066\u3044\u308b\u914d\u5217\u30ea\u30c6\u30e9\u30eb\u306b\u5bfe\u3059\u308b<code>len<\/code>\u306f\u30b3\u30f3\u30d1\u30a4\u30eb\u6642\u5b9a\u6570\u3068\u306a\u308a\u5f97\u307e\u3059\uff08Go\u4ed5\u69d8\u3088\u308a\uff09<\/p>\n<\/blockquote>\n<pre class=\"code lang-go\" data-lang=\"go\" data-unlink=\"\"><span class=\"synStatement\">const<\/span> c1 = <span class=\"synConstant\">1.0<\/span>\n<span class=\"synStatement\">const<\/span> c2 = <span class=\"synStatement\">len<\/span>([<span class=\"synConstant\">10<\/span>]<span class=\"synType\">float64<\/span>{<span class=\"synConstant\">2<\/span>})         \n<span class=\"synStatement\">const<\/span> c3 = <span class=\"synStatement\">len<\/span>([<span class=\"synConstant\">10<\/span>]<span class=\"synType\">float64<\/span>{c1})        \n<\/pre>\n<p><em>Fig. 1. \u30b3\u30f3\u30d1\u30a4\u30eb\u6642\u5b9a\u6570\u3068\u306a\u308b<code>len<\/code>\u306e\u4f8b<\/em><\/p>\n<p>\u4ee5\u4e0a\u306e\u4ed5\u69d8\u304b\u3089\u3001<code>len<\/code>\u306f\u4ed6\u306e\u8a00\u8a9e\u306b\u304a\u3051\u308b\u901a\u5e38\u306e\u95a2\u6570\u3068\u3044\u3046\u3088\u308a<strong>\u6f14\u7b97\u5b50\u7684\u306a\u6027\u8cea<\/strong>\u3092\u6301\u3064\u8a2d\u8a08\u306b\u306a\u3063\u3066\u3044\u308b\u3053\u3068\u304c\u5206\u304b\u308a\u307e\u3059\u3002\u305d\u306e\u5834\u3067\u5024\u3092\u8a08\u7b97\u3059\u308b\u3068\u3044\u3046\u3088\u308a\u3082\u3001\u300c\u3053\u306e\u5024\uff08\u307e\u305f\u306f\u578b\uff09\u306e\u9577\u3055\u300d\u3068\u3044\u3046\u30d3\u30eb\u30c8\u30a4\u30f3\u306e\u30d7\u30ed\u30d1\u30c6\u30a3\u3092\u8fd4\u3059\u3082\u306e\u3068\u3057\u3066\u6271\u308f\u308c\u307e\u3059\u3002<\/p>\n<h2 id=\"\u30b3\u30f3\u30d1\u30a4\u30e9\u5185\u90e8\u3067\u306elen\u51e6\u7406\u30d5\u30ed\u30fc\">\u30b3\u30f3\u30d1\u30a4\u30e9\u5185\u90e8\u3067\u306e<code>len<\/code>\u51e6\u7406\u30d5\u30ed\u30fc<\/h2>\n<p><code>len<\/code>\u306f\u7d44\u307f\u8fbc\u307f\u95a2\u6570\u3068\u3057\u3066<strong>\u30b3\u30f3\u30d1\u30a4\u30e9\u306b\u7279\u5225\u6271\u3044<\/strong>\u3055\u308c\u307e\u3059\u3002Go\u30b3\u30f3\u30d1\u30a4\u30e9\u306f\u69cb\u6587\u89e3\u6790\u30fb\u578b\u30c1\u30a7\u30c3\u30af\u30fbSSA\u5909\u63db\u30fb\u6700\u9069\u5316\u30fb\u30b3\u30fc\u30c9\u751f\u6210\u3068\u3044\u3063\u305f\u8907\u6570\u306e\u30d5\u30a7\u30fc\u30ba\u3092\u7d4c\u3066\u30bd\u30fc\u30b9\u30b3\u30fc\u30c9\u3092\u6a5f\u68b0\u8a9e\u306b\u5909\u63db\u3057\u307e\u3059\u3002\u3053\u3053\u3067\u306f<code>len<\/code>\u304c\u30bd\u30fc\u30b9\u304b\u3089\u3069\u306e\u3088\u3046\u306b\u30b3\u30f3\u30d1\u30a4\u30eb\u3055\u308c\u3066\u3044\u304f\u304b\u3001\u4e3b\u8981\u306a\u6bb5\u968e\u3054\u3068\u306b\u8ffd\u3063\u3066\u307f\u307e\u3057\u3087\u3046\u3002<\/p>\n<h3 id=\"Universe\u30d6\u30ed\u30c3\u30af\u3078\u306e\u7d44\u307f\u8fbc\u307f\u95a2\u6570\u767b\u9332\">Universe\u30d6\u30ed\u30c3\u30af\u3078\u306e\u7d44\u307f\u8fbc\u307f\u95a2\u6570\u767b\u9332<\/h3>\n<p>Go\u3067\u306f<strong>Universe\u30d6\u30ed\u30c3\u30af<\/strong>\u3068\u547c\u3070\u308c\u308b\u7279\u5225\u306a\u9818\u57df\u306b\u3001\u7d44\u307f\u8fbc\u307f\u306e\u5b9a\u6570\u30fb\u578b\u30fb\u95a2\u6570\u304c\u3042\u3089\u304b\u3058\u3081\u5b9a\u7fa9\u3055\u308c\u3066\u3044\u307e\u3059\u3002<code>len<\/code>\u3082\u3053\u306e\u4e2d\u3067\u5b9a\u7fa9\u3055\u308c\u3066\u304a\u308a\u3001\u30b3\u30f3\u30d1\u30a4\u30e9\u8d77\u52d5\u6642\u306b\u4e0b\u8a18\u306e\u3088\u3046\u306b\u767b\u9332\u3055\u308c\u307e\u3059\uff08<code>len<\/code>\u306f\u5185\u90e8\u7684\u306a\u6f14\u7b97\u30b3\u30fc\u30c9<code>OLEN<\/code>\u306b\u5bfe\u5fdc\u4ed8\u3051\u3089\u308c\u307e\u3059\uff09\u3002<\/p>\n<pre class=\"code lang-go\" data-lang=\"go\" data-unlink=\"\">{<span class=\"synConstant\">\"append\"<\/span>, ir.OAPPEND},\n{<span class=\"synConstant\">\"cap\"<\/span>,    ir.OCAP},\n{<span class=\"synConstant\">\"clear\"<\/span>,  ir.OCLEAR},\n{<span class=\"synConstant\">\"close\"<\/span>,  ir.OCLOSE},\n{<span class=\"synConstant\">\"complex\"<\/span>,ir.OCOMPLEX},\n{<span class=\"synConstant\">\"copy\"<\/span>,   ir.OCOPY},\n{<span class=\"synConstant\">\"delete\"<\/span>, ir.ODELETE},\n{<span class=\"synConstant\">\"imag\"<\/span>,   ir.OIMAG},\n{<span class=\"synConstant\">\"len\"<\/span>,    ir.OLEN},\n{<span class=\"synConstant\">\"make\"<\/span>,   ir.OMAKE},\n...\n<\/pre>\n<p><em>Fig. 2. \u7d44\u307f\u8fbc\u307f\u95a2\u6570\u3068\u5185\u90e8\u30b3\u30fc\u30c9\u306e\u5bfe\u5fdc\uff08<code>len<\/code>\u306f<code>ir.OLEN<\/code>\u3068\u3057\u3066\u767b\u9332\uff09<\/em><\/p>\n<p>\u4e0a\u8a18\u306f\u30b3\u30f3\u30d1\u30a4\u30e9\u5185\u90e8 (<a target=\"_blank\" href=\"https:\/\/github.com\/golang\/go\/blob\/master\/src\/cmd\/compile\/internal\/typecheck\/universe.go#L34-L43\"><code>cmd\/compile\/internal\/typecheck\/universe.go<\/code><\/a>) \u3067\u306e<code>builtinFuncs<\/code>\u914d\u5217\u306e\u4e00\u90e8\u3067\u3059\u3002\u30b3\u30f3\u30d1\u30a4\u30e9\u306f\u3053\u308c\u3092\u4f7f\u3063\u3066\u3001\u30bd\u30fc\u30b9\u4e2d\u3067<code>len<\/code>\u3068\u3044\u3046\u8b58\u5225\u5b50\u3092\u898b\u3064\u3051\u305f\u969b\u306b\u901a\u5e38\u306e\u95a2\u6570\u3067\u306f\u306a\u304f<strong>\u7d44\u307f\u8fbc\u307f\u95a2\u6570\u3068\u3057\u3066\u51e6\u7406<\/strong>\u3057\u307e\u3059\u3002\u5b9f\u969b\u3001\u69cb\u6587\u89e3\u6790\u306e\u6bb5\u968e\u3067<code>len(x)<\/code>\u3068\u3044\u3046\u69cb\u6587\u3092\u8aad\u307f\u8fbc\u3080\u3068\u3001<code>len<\/code>\u306f\u5358\u306a\u308b\u95a2\u6570\u547c\u3073\u51fa\u3057\u3067\u306f\u306a\u304f\u300c\u7d44\u307f\u8fbc\u307f\u95a2\u6570<code>len<\/code>\u306e\u9069\u7528\u300d\u3068\u3044\u3046\u7279\u5225\u306a\u30ce\u30fc\u30c9\u3068\u3057\u3066AST\uff08\u62bd\u8c61\u69cb\u6587\u6728\uff09\u306b\u683c\u7d0d\u3055\u308c\u307e\u3059\u3002<\/p>\n<h3 id=\"\u578b\u30c1\u30a7\u30c3\u30af\u3068AST\u5909\u63db\">\u578b\u30c1\u30a7\u30c3\u30af\u3068AST\u5909\u63db<\/h3>\n<p>\u69cb\u6587\u89e3\u6790\u5f8c\u3001\u30b3\u30f3\u30d1\u30a4\u30e9\u306fAST\u4e0a\u3067\u5404\u30ce\u30fc\u30c9\u306e\u578b\u30c1\u30a7\u30c3\u30af\u3092\u884c\u3044\u3001\u4e0d\u6b63\u306a\u64cd\u4f5c\u3092\u691c\u51fa\u3057\u305f\u308a\u5fc5\u8981\u306a\u5909\u63db\u3092\u65bd\u3057\u305f\u308a\u3057\u307e\u3059\u3002<code>len<\/code>\u306b\u3064\u3044\u3066\u306f<strong>\u95a2\u6570\u547c\u3073\u51fa\u3057\u3067\u306f\u306a\u304f\u5358\u9805\u6f14\u7b97\u5b50\u7684\u306a\u6271\u3044<\/strong>\u306b\u306a\u308b\u305f\u3081\u3001\u578b\u30c1\u30a7\u30c3\u30af\u6bb5\u968e\u3067AST\u30ce\u30fc\u30c9\u304c\u5909\u63db\u3055\u308c\u307e\u3059\u3002\u5177\u4f53\u7684\u306b\u306f\u3001<code>len(x)<\/code>\u306b\u5bfe\u5fdc\u3059\u308b\u30ce\u30fc\u30c9\u306f<code>ir.UnaryExpr<\/code>\uff08\u5358\u9805\u5f0f\uff09\u306b\u7f6e\u304d\u63db\u3048\u3089\u308c\u3001\u305d\u306e\u64cd\u4f5c\u7a2e\u5225\u3068\u3057\u3066<code>ir.OLEN<\/code>\u304c\u8a2d\u5b9a\u3055\u308c\u307e\u3059\u3002<\/p>\n<p>\u307e\u305f\u578b\u30c1\u30a7\u30c3\u30af\u4e2d\u306b\u3001<code>len<\/code>\u306e\u5f15\u6570\u306e\u578b\u304c\u6b63\u3057\u3044\u304b\u3069\u3046\u304b\u3092\u691c\u8a3c\u3057\u307e\u3059\u3002Go\u30b3\u30f3\u30d1\u30a4\u30e9\u5185\u90e8\u3067\u306f\u5148\u8ff0\u306e\u901a\u308a<code>len<\/code>\u304c\u9069\u7528\u53ef\u80fd\u306a\u578b\u3092\u4e88\u3081\u30d5\u30e9\u30b0\u30c6\u30fc\u30d6\u30eb<code>okforlen<\/code>\u3067\u5b9a\u7fa9\u3057\u3066\u304a\u308a\u3001\u4f8b\u3048\u3070\u914d\u5217\u30fb\u30c1\u30e3\u30cd\u30eb\u30fb\u30de\u30c3\u30d7\u30fb\u30b9\u30e9\u30a4\u30b9\u30fb\u6587\u5b57\u5217\u306b\u5bfe\u3057\u3066<code>len<\/code>\u304c\u4f7f\u3048\u308b\u3088\u3046\u771f\u306b\u8a2d\u5b9a\u3055\u308c\u3066\u3044\u307e\u3059(<a target=\"_blank\" href=\"https:\/\/github.com\/golang\/go\/blob\/master\/src\/cmd\/compile\/internal\/typecheck\/universe.go#L143-L147\"><code>src\/cmd\/compile\/internal\/typecheck\/universe.go<\/code><\/a>)\u3002<\/p>\n<pre class=\"code lang-go\" data-lang=\"go\" data-unlink=\"\">okforlen[types.TARRAY]  = <span class=\"synStatement\">true<\/span>\nokforlen[types.TCHAN]   = <span class=\"synStatement\">true<\/span>\nokforlen[types.TMAP]    = <span class=\"synStatement\">true<\/span>\nokforlen[types.TSLICE]  = <span class=\"synStatement\">true<\/span>\nokforlen[types.TSTRING] = <span class=\"synStatement\">true<\/span>\n<\/pre>\n<p><em>Fig. 3. \u7d44\u307f\u8fbc\u307f\u95a2\u6570<code>len<\/code>\u304c\u9069\u7528\u53ef\u80fd\u306a\u578b\u306e\u5b9a\u7fa9\uff08\u30b3\u30f3\u30d1\u30a4\u30e9\u5185\u90e8\u30c6\u30fc\u30d6\u30eb\uff09<\/em><\/p>\n<p>\u578b\u30c1\u30a7\u30c3\u30af\u95a2\u6570<code>typecheck1<\/code>\u5185\u3067\u306f\u3001\u30ce\u30fc\u30c9\u306e\u7a2e\u985e\u304c<code>OLEN<\/code>\uff08\u307e\u305f\u306f<code>OCAP<\/code>\uff09\u306e\u5834\u5408\u306b\u5c02\u7528\u306e\u51e6\u7406\u306b\u5206\u5c90\u3057(<a target=\"_blank\" href=\"https:\/\/github.com\/golang\/go\/blob\/master\/src\/cmd\/compile\/internal\/typecheck\/typecheck.go\"><code>src\/cmd\/compile\/internal\/typecheck\/typecheck.go<\/code><\/a>)\u3001\u95a2\u6570<code>tcLenCap<\/code>\u3067\u8a73\u7d30\u306a\u30c1\u30a7\u30c3\u30af\u3068\u578b\u8a2d\u5b9a\u3092\u884c\u3044\u307e\u3059(<a target=\"_blank\" href=\"https:\/\/github.com\/golang\/go\/blob\/master\/src\/cmd\/compile\/internal\/typecheck\/expr.go#L633-L659\"><code>src\/cmd\/compile\/internal\/typecheck\/expr.go<\/code><\/a>)\u3002\u305d\u306e\u5b9f\u88c5\u30b3\u30fc\u30c9\u306e\u6982\u7565\u3092Fig. 4\u306b\u793a\u3057\u307e\u3059\u3002<\/p>\n<pre class=\"code lang-go\" data-lang=\"go\" data-unlink=\"\"><span class=\"synStatement\">switch<\/span> n.Op() {\n    ...\n    <span class=\"synStatement\">case<\/span> ir.OCAP, ir.OLEN:\n        n := n.(*ir.UnaryExpr)\n        <span class=\"synStatement\">return<\/span> tcLenCap(n)\n}\n\n\n<span class=\"synStatement\">func<\/span> tcLenCap(n *ir.UnaryExpr) ir.Node {\n    n.X = Expr(n.X)\n    n.X = DefaultLit(n.X, <span class=\"synStatement\">nil<\/span>)\n    n.X = implicitstar(n.X)\n    ...\n    <span class=\"synStatement\">var<\/span> ok <span class=\"synType\">bool<\/span>\n    <span class=\"synStatement\">if<\/span> n.Op() == ir.OLEN {\n        ok = okforlen[t.Kind()]\n    } <span class=\"synStatement\">else<\/span> {\n        ok = okforcap[t.Kind()]\n    }\n    <span class=\"synStatement\">if<\/span> !ok {\n        base.Errorf(<span class=\"synConstant\">\"invalid argument %L for %v\"<\/span>, l, n.Op())\n        n.SetType(<span class=\"synStatement\">nil<\/span>)\n        <span class=\"synStatement\">return<\/span> n\n    }\n    n.SetType(types.Types[types.TINT])\n    <span class=\"synStatement\">return<\/span> n\n}\n<\/pre>\n<p><em>Fig. 4. <code>len<\/code>\/<code>cap<\/code>\u30ce\u30fc\u30c9\u306e\u578b\u30c1\u30a7\u30c3\u30af\u51e6\u7406\uff08\u4e0d\u6b63\u306a\u578b\u306a\u3089\u30a8\u30e9\u30fc\u3057\u3001\u623b\u308a\u5024\u578b\u3092<code>int<\/code>\u306b\u8a2d\u5b9a\uff09<\/em><\/p>\n<p>\u4e0a\u8a18\u306e\u3088\u3046\u306b\u3001\u307e\u305a<code>len<\/code>\u306e\u5f15\u6570<code>n.X<\/code>\u3092\u518d\u5e30\u7684\u306b\u5f0f\u3068\u3057\u3066\u578b\u30c1\u30a7\u30c3\u30af\u3057\uff08<code>Expr(n.X)<\/code>\u7b49\uff09\u3001\u30c7\u30d5\u30a9\u30eb\u30c8\u306e\u30ea\u30c6\u30e9\u30eb\u578b\u9069\u7528\u3084\u30dd\u30a4\u30f3\u30bf\u9593\u63a5\u306e\u6697\u9ed9\u7684\u633f\u5165\uff08<code>implicitstar<\/code>\uff09\u3092\u884c\u3063\u305f\u5f8c\u3001<code>okforlen<\/code>\u30c6\u30fc\u30d6\u30eb\u3092\u53c2\u7167\u3057\u3066\u5f15\u6570\u578b\u304c\u8a31\u5bb9\u3055\u308c\u308b\u304b\u691c\u67fb\u3057\u3066\u3044\u307e\u3059\u3002\u3082\u3057\u8a31\u53ef\u3055\u308c\u306a\u3044\u578b\u3067\u3042\u308c\u3070\u30a8\u30e9\u30fc\u3092\u5831\u544a\u3057\uff08invalid argument for <code>len<\/code>\uff09\u3001\u30ce\u30fc\u30c9\u306e\u578b\u3092<code>nil<\/code>\u306b\u3057\u3066\u7d42\u4e86\u3057\u307e\u3059\u3002\u554f\u984c\u306a\u3051\u308c\u3070\u3001<code>len<\/code>\u30ce\u30fc\u30c9\u81ea\u4f53\u306e\u578b\uff08<code>n.Type<\/code>\uff09\u3092<code>int<\/code>\u578b\u306b\u8a2d\u5b9a\u3057\u307e\u3059\u3002\u3053\u308c\u306b\u3088\u308a\u3001\u3053\u306e\u6642\u70b9\u3067\u30b3\u30f3\u30d1\u30a4\u30e9\u306f\u300c<code>len(x)<\/code>\u306e\u7d50\u679c\u306f<code>int<\/code>\u3067\u3042\u308b\u300d\u3053\u3068\u3092AST\u4e0a\u3067\u78ba\u5b9a\u3055\u305b\u308b\u308f\u3051\u3067\u3059\u3002<\/p>\n<p>\u578b\u30c1\u30a7\u30c3\u30af\u6bb5\u968e\u307e\u3067\u3067\u7279\u306b\u91cd\u8981\u306a\u306e\u306f\u3001<code>len<\/code>\u304c<strong>\u5b9f\u969b\u306e\u95a2\u6570\u547c\u3073\u51fa\u3057\u3067\u306f\u306a\u304f\u30b3\u30f3\u30d1\u30a4\u30e9\u5185\u90e8\u3067\u7279\u5225\u6271\u3044\u3055\u308c\u308b<\/strong>\u70b9\u3067\u3059\u3002Go\u306e\u7d44\u307f\u8fbc\u307f<code>builtin.go<\/code>\u306b\u306f<code>func len(v Type) int<\/code>\u3068\u5ba3\u8a00\u3055\u308c\u3066\u3044\u307e\u3059\u304c\u5b9f\u4f53\u306f\u306a\u304f\u3001IDE\u306a\u3069\u3067\u5b9a\u7fa9\u3092\u898b\u3066\u3082\u7a7a\u3063\u307d\u306a\u95a2\u6570\u304c\u51fa\u3066\u304f\u308b\u3060\u3051\u3067\u3059\u3002\u3053\u308c\u306f\u30b3\u30f3\u30d1\u30a4\u30e9\u304c\u30d3\u30eb\u30c8\u30a4\u30f3\u3092\u76f4\u63a5\u51e6\u7406\u3059\u308b\u305f\u3081\u3067\u3001<code>len<\/code>\u306f\u30e6\u30fc\u30b6\u304c\u5b9f\u88c5\u3092\u898b\u308b\u3088\u3046\u306a\u901a\u5e38\u306e\u95a2\u6570\u3067\u306f\u306a\u3044\u306e\u3067\u3059\u3002<\/p>\n<h3 id=\"SSA\u5f62\u5f0f\u3078\u306e\u5909\u63db\u4e2d\u9593\u8868\u73fe\">SSA\u5f62\u5f0f\u3078\u306e\u5909\u63db\uff08\u4e2d\u9593\u8868\u73fe\uff09<\/h3>\n<p>\u3059\u3079\u3066\u306e\u578b\u30c1\u30a7\u30c3\u30af\u304c\u7d42\u308f\u308b\u3068\u3001\u6b21\u306f<strong>SSA\u5f62\u5f0f<\/strong>\u3078\u306e\u5909\u63db\uff08\u9759\u7684\u5358\u4e00\u4ee3\u5165\u5f62\u5f0f\u306e\u4e2d\u9593\u8868\u73fe\uff09\u306b\u5165\u308a\u307e\u3059\u3002Go\u30b3\u30f3\u30d1\u30a4\u30e9\u3067\u306f\u5404\u95a2\u6570\u3054\u3068\u306bAST\u304b\u3089SSA\u3092\u69cb\u7bc9\u3057\u3001\u6700\u9069\u5316\u3092\u884c\u3063\u305f\u5f8c\u3001\u6a5f\u68b0\u8a9e\u306e\u751f\u6210\u3078\u3068\u9032\u307f\u307e\u3059\u3002<code>len<\/code>\u306b\u3064\u3044\u3066\u306fSSA\u751f\u6210\u6642\u306b\u3055\u3089\u306b\u5404\u578b\u3054\u3068\u306b\u6271\u3044\u304c\u5206\u5c90\u3057\u307e\u3059\u3002\u305d\u306e\u51e6\u7406\u3092\u793a\u3057\u305f\u306e\u304c\u4ee5\u4e0b\u306e\u30b3\u30fc\u30c9\u3067\u3059(<a target=\"_blank\" href=\"https:\/\/github.com\/golang\/go\/blob\/master\/src\/cmd\/compile\/internal\/ssagen\/ssa.go#L3429-L3453\"><code>src\/cmd\/compile\/internal\/ssagen\/ssa.go<\/code><\/a>)<\/p>\n<pre class=\"code lang-go\" data-lang=\"go\" data-unlink=\"\">\n<span class=\"synStatement\">func<\/span> (s *state) expr(n ir.Node) *ssa.Value {\n    ...\n    <span class=\"synStatement\">switch<\/span> n.Op() {\n    <span class=\"synStatement\">case<\/span> ir.OLEN, ir.OCAP:\n        n := n.(*ir.UnaryExpr)\n        \n        \n        a := s.expr(n.X)\n        t := n.X.Type()\n        <span class=\"synStatement\">switch<\/span> {\n        <span class=\"synStatement\">case<\/span> t.IsSlice():\n            op := ssa.OpSliceLen\n            <span class=\"synStatement\">if<\/span> n.Op() == ir.OCAP {\n                op = ssa.OpSliceCap\n            }\n            <span class=\"synStatement\">return<\/span> s.newValue1(op, types.Types[types.TINT], a)\n        <span class=\"synStatement\">case<\/span> t.IsString(): \n            <span class=\"synStatement\">return<\/span> s.newValue1(ssa.OpStringLen, types.Types[types.TINT], a)\n        <span class=\"synStatement\">case<\/span> t.IsMap(), t.IsChan():\n            <span class=\"synStatement\">return<\/span> s.referenceTypeBuiltin(n, a)\n        <span class=\"synStatement\">case<\/span> t.IsArray():\n            <span class=\"synStatement\">return<\/span> s.constInt(types.Types[types.TINT], t.NumElem())\n}\n<\/pre>\n<p><em>Fig. 5. <code>len<\/code>\/<code>cap<\/code>\u30ce\u30fc\u30c9\u306eSSA\u5909\u63db\u51e6\u7406\uff08\u5f15\u6570\u306e\u578b\u306b\u5fdc\u3058\u3066\u7570\u306a\u308bSSA\u547d\u4ee4\u3084\u5b9a\u6570\u306b\u5c55\u958b\uff09<\/em><\/p>\n<p>\u4e0a\u8a18\u306e\u3088\u3046\u306b\u3001SSA\u751f\u6210\u30d5\u30a7\u30fc\u30ba\u3067\u306f<code>len<\/code>(\u304a\u3088\u3073<code>cap<\/code>)\u306b\u5bfe\u3057\u4ee5\u4e0b\u306e\u3088\u3046\u306a\u5206\u5c90\u51e6\u7406\u304c\u884c\u308f\u308c\u307e\u3059\u3002<\/p>\n<ul>\n<li>\u5f15\u6570\u304c<strong>\u914d\u5217\u578b<\/strong>\u306e\u5834\u5408\uff08\u30c7\u30d5\u30a9\u30eb\u30c8\u30b1\u30fc\u30b9\uff09 \u2014 <code>n.X.Type().NumElem()<\/code>\u3067\u914d\u5217\u8981\u7d20\u6570\u3092\u53d6\u5f97\u3057\u3001\u5358\u306b\u305d\u306e\u5024\u3092\u5b9a\u6570\uff08SSA\u4e0a\u306e\u5b9a\u6570\u5024\uff09\u3068\u3057\u3066\u8fd4\u3057\u307e\u3059\u3002\u3059\u306a\u308f\u3061\u3001\u30b3\u30f3\u30d1\u30a4\u30eb\u6642\u70b9\u3067\u914d\u5217\u9577\u304c\u5206\u304b\u308b\u5834\u5408\u3001SSA\u4e0a\u3067\u306f\u65e2\u306b\u30ea\u30c6\u30e9\u30eb\u306a\u5b9a\u6570\u3068\u306a\u308a\u307e\u3059\u3002\u4f8b\u3048\u3070<code>[5]int<\/code>\u578b\u306e\u5909\u6570\u3067\u3042\u308c\u3070\u3001\u305d\u306e<code>len<\/code>\u306f5\u3068\u3044\u3046\u5b9a\u6570\u306b\u306a\u308a\u307e\u3059\u3002\u3053\u306e\u5b9f\u88c5\u3067\u306f\u30b3\u30f3\u30d1\u30a4\u30eb\u6642\u306b\u578b\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u304b\u3089<code>NumElem()<\/code>\u30e1\u30bd\u30c3\u30c9\u3067\u914d\u5217\u9577\uff08\u5185\u90e8\u7684\u306b\u306f\u578b\u60c5\u5831\u4e2d\u306e<code>Bound<\/code>\u30d5\u30a3\u30fc\u30eb\u30c9\uff09\u3092\u53d6\u5f97\u3057\u3066\u3044\u307e\u3059\uff08Fig. 5\u4e2d\u306e<code>t.NumElem()<\/code>\u90e8\u5206\uff09\u3002<\/li>\n<li>\u5f15\u6570\u304c<strong>\u30b9\u30e9\u30a4\u30b9\u578b<\/strong>\u306e\u5834\u5408 \u2014 <code>ssa.OpSliceLen<\/code>\u3068\u3044\u3046SSA\u547d\u4ee4\u3092\u751f\u6210\u3057\u307e\u3059\uff08<code>cap<\/code>\u306e\u5834\u5408\u306f<code>ssa.OpSliceCap<\/code>\uff09\u3002\u3053\u308c\u306f\u30b9\u30e9\u30a4\u30b9\u306e\u9577\u3055\u60c5\u5831\u3092\u53d6\u308a\u51fa\u3059\u5c02\u7528\u306eSSA\u547d\u4ee4\u3067\u3059\u3002<\/li>\n<li>\u5f15\u6570\u304c<strong>\u6587\u5b57\u5217\u578b<\/strong>\u306e\u5834\u5408 \u2014 <code>ssa.OpStringLen<\/code>\u3068\u3044\u3046SSA\u547d\u4ee4\u3092\u751f\u6210\u3057\u307e\u3059\u3002\u6587\u5b57\u5217\u306b\u3064\u3044\u3066\u306f<code>cap<\/code>\u306f\u5b58\u5728\u3057\u306a\u3044\u306e\u3067<code>len<\/code>\u306e\u5834\u5408\u3060\u3051\u3067\u3059\u3002<\/li>\n<li>\u5f15\u6570\u304c<strong>\u30de\u30c3\u30d7\u578b\u307e\u305f\u306f\u30c1\u30e3\u30cd\u30eb\u578b<\/strong>\u306e\u5834\u5408 \u2014 <code>s.referenceTypeBuiltin<\/code>\u3068\u3044\u3046\u5c02\u7528\u306e\u30d8\u30eb\u30d1\u30fc\u95a2\u6570\u3092\u547c\u3073\u51fa\u3057\u307e\u3059\u3002\u30de\u30c3\u30d7\u3068\u30c1\u30e3\u30cd\u30eb\u306f\u5185\u90e8\u5b9f\u88c5\u304c\u53c2\u7167\u578b\u3067\u3042\u308b\u305f\u3081\u3001\u3053\u308c\u3089\u306b\u3064\u3044\u3066\u306f\u6c4e\u7528\u7684\u306a\u51e6\u7406\u304c\u53d6\u3089\u308c\u3066\u3044\u307e\u3059\uff08\u3053\u306e\u90e8\u5206\u306f\u6b21\u7bc0\u3067\u8a73\u8aac\uff09\u3002<\/li>\n<\/ul>\n<p>\u3053\u306eSSA\u6bb5\u968e\u306e\u5206\u5c90\u306b\u3088\u308a\u3001<code>len<\/code>\u306e\u52d5\u4f5c\u306f<strong>\u5f15\u6570\u306e\u578b\u3054\u3068\u306b\u6700\u9069\u5316<\/strong>\u3055\u308c\u307e\u3059\u3002\u914d\u5217\u9577\u306f\u5b9a\u6570\u7573\u307f\u8fbc\u307f\u3055\u308c\u3001\u30b9\u30e9\u30a4\u30b9\u30fb\u6587\u5b57\u5217\u9577\u306fSSA\u4e0a\u3067\u5c02\u7528\u547d\u4ee4\uff08\u5f8c\u8ff0\u306e\u3068\u304a\u308a\u6700\u7d42\u7684\u306b\u306f\u5358\u306a\u308b\u30e1\u30e2\u30ea\u30a2\u30af\u30bb\u30b9\u306b\u5909\u308f\u308b\uff09\u3068\u306a\u308a\u3001\u30de\u30c3\u30d7\u30fb\u30c1\u30e3\u30cd\u30eb\u9577\u306f\u591a\u5c11\u8907\u96d1\u306a\u51e6\u7406\uff08<code>nil<\/code>\u30c1\u30a7\u30c3\u30af\u3092\u542b\u3080\u30b3\u30fc\u30c9\uff09\u306b\u5c55\u958b\u3055\u308c\u307e\u3059\u3002<\/p>\n<h3 id=\"\u30b3\u30fc\u30c9\u751f\u6210\u3068\u6700\u9069\u5316\">\u30b3\u30fc\u30c9\u751f\u6210\u3068\u6700\u9069\u5316<\/h3>\n<p>SSA\u30d5\u30a9\u30fc\u30e0\u3078\u306e\u5909\u63db\u5f8c\u3001\u30b3\u30f3\u30d1\u30a4\u30e9\u306f\u30a2\u30fc\u30ad\u30c6\u30af\u30c1\u30e3\u56fa\u6709\u306e\u6700\u9069\u5316\u30fb\u30b3\u30fc\u30c9\u751f\u6210\u3092\u884c\u3044\u307e\u3059\u3002<code>len<\/code>\u306b\u95a2\u3057\u3066\u3082\u3001\u3053\u306e\u6bb5\u968e\u3067SSA\u547d\u4ee4\u304c\u5177\u4f53\u7684\u306a\u6a5f\u68b0\u8a9e\u306b\u7f6e\u304d\u63db\u308f\u308a\u307e\u3059\u3002\u5404\u578b\u306b\u304a\u3051\u308b\u4e3b\u306a\u5909\u63db\u306f\u4ee5\u4e0b\u306e\u3068\u304a\u308a\u3067\u3059\u3002<\/p>\n<ul>\n<li><strong>\u914d\u5217<\/strong>: SSA\u4e0a\u65e2\u306b\u6574\u6570\u5b9a\u6570\u306b\u306a\u3063\u3066\u3044\u308b\u305f\u3081\u3001\u305d\u306e\u307e\u307e\u5373\u5024\u30ea\u30c6\u30e9\u30eb\u3068\u3057\u3066\u30b3\u30fc\u30c9\u4e2d\u306b\u57cb\u3081\u8fbc\u307e\u308c\u307e\u3059\u3002\u5b9f\u884c\u6642\u306e\u8a08\u7b97\u306f\u767a\u751f\u3057\u307e\u305b\u3093\u3002<\/li>\n<li><strong>\u30b9\u30e9\u30a4\u30b9\u30fb\u6587\u5b57\u5217<\/strong>: <code>OpSliceLen<\/code>\u3084<code>OpStringLen<\/code>\u3068\u3044\u3063\u305fSSA\u547d\u4ee4\u306f\u3001\u5b9f\u884c\u6642\u306b\u306f<strong>\u69cb\u9020\u4f53\u306e\u8a72\u5f53\u30d5\u30a3\u30fc\u30eb\u30c9\u3092\u8aad\u307f\u53d6\u308b\u5358\u7d14\u306a\u547d\u4ee4<\/strong>\u306b\u5909\u63db\u3055\u308c\u307e\u3059\u3002Go\u306b\u304a\u3051\u308b\u30b9\u30e9\u30a4\u30b9\u306f\u5b9f\u4f53\u3068\u3057\u3066\u5185\u90e8\u306b\u30dd\u30a4\u30f3\u30bf\u30fb\u9577\u3055\u30fb\u5bb9\u91cf\u306e\u30d5\u30a3\u30fc\u30eb\u30c9\u3092\u6301\u3064\u69cb\u9020\u4f53\u3067\u8868\u73fe\u3055\u308c\u307e\u3059\u3057\u3001\u6587\u5b57\u5217\u3082\u30c7\u30fc\u30bf\u3078\u306e\u30dd\u30a4\u30f3\u30bf\u3068\u9577\u3055\u3092\u6301\u3064\u69cb\u9020\u4f53\u3067\u3059\u3002\u3057\u305f\u304c\u3063\u3066\u3001\u4f8b\u3048\u3070\u30b9\u30e9\u30a4\u30b9\u306e\u9577\u3055\u53d6\u5f97\u306f\u30e1\u30e2\u30ea\u4e0a\u3067\u300c\u30dd\u30a4\u30f3\u30bf\u306e\u76f4\u5f8c\u306b\u3042\u308b<code>int<\/code>\u5024\u300d\u3092\u8aad\u307f\u51fa\u3059\u64cd\u4f5c\u306b\u306a\u308a\u307e\u3059\u3002Go\u30b3\u30f3\u30d1\u30a4\u30e9\u306fSSA\u6700\u9069\u5316\u306e<strong>Late Expansion<\/strong>\u6bb5\u968e\u3067\u3053\u308c\u3089\u3092\u5c55\u958b\u3057\u3001\u30dd\u30a4\u30f3\u30bf\u6f14\u7b97\u3067\u9069\u5207\u306a\u30aa\u30d5\u30bb\u30c3\u30c8\u304b\u3089\u9577\u3055\u3092\u53d6\u308a\u51fa\u3059\u30b3\u30fc\u30c9\u306b\u3057\u307e\u3059\uff08\u5178\u578b\u7684\u306b\u306f\u30dd\u30a4\u30f3\u30bf\u30b5\u30a4\u30ba\u5206\u30aa\u30d5\u30bb\u30c3\u30c8\u3057\u305f\u4f4d\u7f6e\u304clen\u30d5\u30a3\u30fc\u30eb\u30c9\u3067\u3059\uff09\u3002\u5b9f\u969b\u3001x86-64\u30a2\u30fc\u30ad\u30c6\u30af\u30c1\u30e3\u3067\u306f\u30b9\u30e9\u30a4\u30b9\u9577\u306e\u53d6\u5f97\u306f1\u547d\u4ee4\u3067\u5b8c\u4e86\u3057\u307e\u3059\u3002\u4f8b\u3048\u3070\u300c\u30ec\u30b8\u30b9\u30bf\u306b\u5165\u3063\u3066\u3044\u308b\u30b9\u30e9\u30a4\u30b9\u69cb\u9020\u4f53\u306e\u9577\u3055\u30d5\u30a3\u30fc\u30eb\u30c9\u3092\u5225\u306e\u30ec\u30b8\u30b9\u30bf\u306b\u79fb\u3059\u300d\u3068\u3044\u3063\u305f\u5177\u5408\u3067\u3059\u3002<strong>\uff08\u5177\u4f53\u4f8b\u306f\u5f8c\u8ff0\uff09<\/strong><\/li>\n<li><strong>\u30de\u30c3\u30d7\u30fb\u30c1\u30e3\u30cd\u30eb<\/strong>: \u3053\u308c\u3089\u3082\u5185\u90e8\u7684\u306b\u306f\u30dd\u30a4\u30f3\u30bf\u3067\u8868\u73fe\u3055\u308c\u305f\u53c2\u7167\u578b\u3067\u3001runtime\u30d1\u30c3\u30b1\u30fc\u30b8\u5185\u306e\u69cb\u9020\u4f53\uff08<code>hmap<\/code>\u3084<code>hchan<\/code>\uff09\u3068\u3057\u3066\u5b9f\u88c5\u3055\u308c\u3066\u3044\u307e\u3059\u3002<code>len<\/code>\u3092\u6c42\u3081\u308b\u5834\u5408\u3001\u69cb\u9020\u4f53\u306e\u5148\u982d\u306b\u683c\u7d0d\u3055\u308c\u305f\u30d5\u30a3\u30fc\u30eb\u30c9\uff08\u30de\u30c3\u30d7\u306a\u3089\u8981\u7d20\u6570<code>count<\/code>\u3001\u30c1\u30e3\u30cd\u30eb\u306a\u3089\u30ad\u30e5\u30fc\u4e2d\u306e\u8981\u7d20\u6570<code>qcount<\/code>\uff09\u3092\u8aad\u307f\u51fa\u305b\u3070\u826f\u3044\u306e\u3067\u3059\u304c\u3001<strong>\u6ce8\u610f\u70b9\u306f\u30dd\u30a4\u30f3\u30bf\u304c<code>nil<\/code>\u306e\u53ef\u80fd\u6027<\/strong>\u3067\u3059\u3002<code>len(nil)<\/code>\u304c0\u3092\u8fd4\u3059\u3068\u3044\u3046\u4ed5\u69d8\u3092\u5b88\u308b\u305f\u3081\u3001\u30b3\u30f3\u30d1\u30a4\u30e9\u306f<code>nil<\/code>\u30c1\u30a7\u30c3\u30af\u3092\u30b3\u30fc\u30c9\u4e2d\u306b\u7d44\u307f\u8fbc\u307f\u307e\u3059\u3002SSA\u3067\u751f\u6210\u3055\u308c\u305f<code>referenceTypeBuiltin<\/code>\u95a2\u6570\u5185\u306e\u51e6\u7406\u306f\u307e\u3055\u306b\u305d\u308c\u3092\u5b9f\u73fe\u3057\u3066\u3044\u307e\u3059\u3002<\/li>\n<\/ul>\n<p>Fig. 6\u306f<code>referenceTypeBuiltin<\/code>\u95a2\u6570\u5185\u306e\u8a72\u5f53\u90e8\u5206\u3092\u629c\u7c8b\u3057\u305f\u3082\u306e\u3067\u3059(<a target=\"_blank\" href=\"https:\/\/github.com\/golang\/go\/blob\/master\/src\/cmd\/compile\/internal\/ssagen\/ssa.go#L5650-L5715\"><code>src\/cmd\/compile\/internal\/ssagen\/ssa.go<\/code><\/a>)\u3002\u3053\u306e\u30b3\u30fc\u30c9\u306f\u300c\u30de\u30c3\u30d7\/\u30c1\u30e3\u30cd\u30eb\u306e<code>len<\/code>\/<code>cap<\/code>\u7528\u306eSSA\u30b3\u30fc\u30c9\u300d\u3092\u751f\u6210\u3057\u307e\u3059\u3002<\/p>\n<pre class=\"code lang-go\" data-lang=\"go\" data-unlink=\"\">lenType := n.Type()\nnilValue := s.constNil(types.Types[types.TUINTPTR])\ncmp := s.newValue2(ssa.OpEqPtr, types.Types[types.TBOOL], x, nilValue)\nb := s.endBlock()\nb.Kind = ssa.BlockIf\nb.SetControl(cmp)\nb.Likely = ssa.BranchUnlikely\n\nbThen := s.f.NewBlock(ssa.BlockPlain)\nbElse := s.f.NewBlock(ssa.BlockPlain)\nbAfter := s.f.NewBlock(ssa.BlockPlain)\n\n...\n<span class=\"synStatement\">switch<\/span> n.Op() {\n<span class=\"synStatement\">case<\/span> ir.OLEN:\n    \n    s.vars[n] = s.load(lenType, x)\n...\n}\n<span class=\"synStatement\">return<\/span> s.variable(n, lenType)\n<\/pre>\n<p><em>Fig. 6. \u30de\u30c3\u30d7\/\u30c1\u30e3\u30cd\u30eb\u306b\u5bfe\u3059\u308b<code>len<\/code>\/<code>cap<\/code>\u306eSSA\u5c55\u958b\uff08<code>nil<\/code>\u30c1\u30a7\u30c3\u30af\u3068\u9577\u3055\u30d5\u30a3\u30fc\u30eb\u30c9\u8aad\u307f\u53d6\u308a\u306e\u751f\u6210\uff09<\/em><\/p>\n<p>\u3053\u306e\u751f\u6210\u30eb\u30fc\u30c1\u30f3\u3067\u306f\u3001\u307e\u305a\u5f15\u6570\u30dd\u30a4\u30f3\u30bf<code>x<\/code>\u304c<code>nil<\/code>\u3068\u7b49\u3057\u3044\u304b\u6bd4\u8f03\u3059\u308bSSA\u5024\u3092\u4f5c\u308a\uff08<code>OpEqPtr<\/code>\uff09\u3001if\u6587\u30d6\u30ed\u30c3\u30af\u3092\u69cb\u7bc9\u3057\u3066\u3044\u307e\u3059\u3002<code>cmp<\/code>\u304c\u771f\uff08\u3064\u307e\u308a\u30dd\u30a4\u30f3\u30bf\u304c<code>nil<\/code>\uff09\u306e\u5834\u5408\u306f\u300c<code>len<\/code>=0\u300d\u3092\u8fd4\u3059\u7d4c\u8def\u3001\u507d\u306e\u5834\u5408\u306f\u5b9f\u969b\u306b\u9577\u3055\u3092\u8aad\u307f\u53d6\u308b\u7d4c\u8def\u306b\u5206\u5c90\u3059\u308b\u5f62\u3067\u3059\u3002\u5b9f\u969b\u306e\u9577\u3055\u8aad\u307f\u53d6\u308a\u306f\u3001<code>s.load(lenType, x)<\/code>\u306b\u3088\u3063\u3066\u884c\u308f\u308c\u307e\u3059\u3002\u3053\u308c\u306f\u4e0e\u3048\u3089\u308c\u305f\u30dd\u30a4\u30f3\u30bf<code>x<\/code>\uff08\u30de\u30c3\u30d7\u307e\u305f\u306f\u30c1\u30e3\u30cd\u30eb\uff09\u304b\u3089<code>lenType<\/code>\uff08<code>int<\/code>\u578b\uff09\u306e\u5024\u3092\u8aad\u307f\u53d6\u308b\u3001\u3064\u307e\u308a\u69cb\u9020\u4f53\u306e\u5148\u982d\u306e<code>int<\/code>\u30d5\u30a3\u30fc\u30eb\u30c9\u3092\u8aad\u307f\u51fa\u3059\u3053\u3068\u3092\u610f\u5473\u3057\u307e\u3059\u3002\u4e0a\u8ff0\u306e\u3088\u3046\u306b\u30de\u30c3\u30d7\u3067\u306f\u5148\u982d\u306b<code>count<\/code>\u3001\u30c1\u30e3\u30cd\u30eb\u3067\u306f\u5148\u982d\u306b<code>qcount<\/code>\u304c\u3042\u308b\u305f\u3081\u3001\u3061\u3087\u3046\u3069\u305d\u308c\u304c<code>len<\/code>\u306e\u8fd4\u3059\u3079\u304d\u5024\u306b\u306a\u3063\u3066\u3044\u307e\u3059\u3002<\/p>\n<p>\u6700\u5f8c\u306b<code>return s.variable(n, lenType)<\/code>\u3068\u3059\u308b\u3053\u3068\u3067\u3001\u3053\u306e\u8a08\u7b97\u7d50\u679c\u3092SSA\u4e0a\u306e\u5909\u6570\uff08\u4eee\u60f3\u30ec\u30b8\u30b9\u30bf\uff09\u3068\u3057\u3066<code>len<\/code>\u30ce\u30fc\u30c9\u306b\u5bfe\u5fdc\u4ed8\u3051\u3066\u3044\u307e\u3059\u3002\u3053\u3046\u3057\u3066SSA\u4e0a\u3067\u306f\u3001<code>nil<\/code>\u5206\u5c90\u3068\u8aad\u307f\u53d6\u308a\u30b3\u30fc\u30c9\u304c\u8868\u73fe\u3055\u308c\u3001\u6700\u7d42\u7684\u306b\u30d0\u30c3\u30af\u30a8\u30f3\u30c9\u3067\u3053\u308c\u304c\u5177\u4f53\u7684\u306a\u5206\u5c90\u547d\u4ee4\u3068\u30e1\u30e2\u30ea\u30a2\u30af\u30bb\u30b9\u547d\u4ee4\u306b\u5909\u63db\u3055\u308c\u307e\u3059\u3002<\/p>\n<h2 id=\"\u578b\u3054\u3068\u306elen\u306e\u6319\u52d5\u3068\u5b9f\u88c5\u8a73\u7d30\">\u578b\u3054\u3068\u306e<code>len<\/code>\u306e\u6319\u52d5\u3068\u5b9f\u88c5\u8a73\u7d30<\/h2>\n<p>\u4ee5\u4e0a\u3001\u30b3\u30f3\u30d1\u30a4\u30e9\u5185\u90e8\u3067\u306e\u5909\u63db\u51e6\u7406\u3092\u898b\u3066\u304d\u307e\u3057\u305f\u3002\u3053\u3053\u3067\u6539\u3081\u3066\u3001\u5404\u30c7\u30fc\u30bf\u578b\u306b\u3064\u3044\u3066<code>len<\/code>\u304c\u3069\u306e\u3088\u3046\u306b\u52d5\u4f5c\u3057\u3001\u6700\u7d42\u7684\u306b\u3069\u3093\u306a\u30b3\u30fc\u30c9\u306b\u306a\u308b\u306e\u304b\u3092\u307e\u3068\u3081\u307e\u3059\u3002<\/p>\n<h3 id=\"\u914d\u5217\u306b\u5bfe\u3059\u308blen\">\u914d\u5217\u306b\u5bfe\u3059\u308b<code>len<\/code><\/h3>\n<p>\u914d\u5217\u578b\uff08<code>[n]T<\/code>\uff09\u306b\u5bfe\u3059\u308b<code>len<\/code>\u306f<strong>\u30b3\u30f3\u30d1\u30a4\u30eb\u6642\u306b\u6c7a\u307e\u308b\u5b9a\u6570<\/strong>\u3067\u3059\u3002\u914d\u5217\u306e\u9577\u3055<code>n<\/code>\u306f\u305d\u306e\u578b\u306e\u4e00\u90e8\u3067\u3042\u308a\u3001Go\u3067\u306f\u30b3\u30f3\u30d1\u30a4\u30eb\u6642\u306b\u914d\u5217\u30b5\u30a4\u30ba\u304c\u78ba\u5b9a\u3057\u3066\u3044\u307e\u3059\u3002\u3057\u305f\u304c\u3063\u3066\u3001\u914d\u5217\u5909\u6570\u3084\u914d\u5217\u30ea\u30c6\u30e9\u30eb\u306b\u5bfe\u3059\u308b<code>len<\/code>\u306f\u3001\u30b3\u30f3\u30d1\u30a4\u30e9\u304c\u305d\u306e\u5834\u3067<code>n<\/code>\u3068\u3044\u3046\u5b9a\u6570\u5024\u306b\u7f6e\u304d\u63db\u3048\u307e\u3059\u3002<\/p>\n<pre class=\"code lang-go\" data-lang=\"go\" data-unlink=\"\"><span class=\"synStatement\">var<\/span> a [<span class=\"synConstant\">5<\/span>]<span class=\"synType\">int<\/span>\nfmt.Println(<span class=\"synStatement\">len<\/span>(a))  \n<\/pre>\n<p><em>Fig. 7. \u914d\u5217\u306b\u5bfe\u3059\u308b<code>len<\/code>\u306e\u4f7f\u7528\u4f8b\uff08\u30b3\u30f3\u30d1\u30a4\u30eb\u6642\u306b\u5b9a\u65705\u306b\u7f6e\u304d\u63db\u308f\u308b\uff09<\/em><\/p>\n<p>\u4e0a\u8a18<code>len(a)<\/code>\u306f\u5b9f\u884c\u6642\u306e\u8a08\u7b97\u3092\u5fc5\u8981\u3068\u305b\u305a\u3001\u751f\u6210\u3055\u308c\u308b\u30b3\u30fc\u30c9\u4e0a\u3067\u306f\u5b9a\u65705\u3068\u3057\u3066\u6271\u308f\u308c\u307e\u3059\u3002\u4eee\u306b\u30dd\u30a4\u30f3\u30bf\u578b<code>*[5]int<\/code>\u3067\u3042\u3063\u3066\u3082\u3001\u6307\u3057\u3066\u3044\u308b\u914d\u5217\u9577\u306f5\u3068\u6c7a\u307e\u3063\u3066\u3044\u308b\u305f\u3081\u3001\u540c\u69d8\u306b<code>len(p)<\/code>\u306f5\u3068\u306a\u308a\u307e\u3059\u3002\u305f\u3060\u3057\u3001\u30dd\u30a4\u30f3\u30bf\u304c<code>nil<\/code>\u3067\u3042\u3063\u3066\u3082\u914d\u5217\u9577\u81ea\u4f53\u306f\u578b\u304b\u3089\u5206\u304b\u308b\u305f\u3081\u3001<code>(*[5]int)(nil)<\/code>\u306b\u5bfe\u3059\u308b<code>len<\/code>\u30825\u3092\u8fd4\u3057\u307e\u3059\uff08\u3082\u3063\u3068\u3082\u3001\u305d\u306e\u3088\u3046\u306a\u30b3\u30fc\u30c9\u3092\u66f8\u304f\u3053\u3068\u306f\u7a00\u3067\u3059\u304c\u3001\u4ed5\u69d8\u4e0a\u305d\u3046\u306a\u3063\u3066\u3044\u307e\u3059\uff09\u3002<\/p>\n<p>\u30b3\u30f3\u30d1\u30a4\u30e9\u5b9f\u88c5\u7684\u306b\u306f\u3001\u914d\u5217\u9577\u306f\u578b\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u5185\u306e\u30d5\u30a3\u30fc\u30eb\u30c9\uff08<code>types.Array.Bound<\/code><a target=\"_blank\" href=\"https:\/\/github.com\/golang\/go\/blob\/master\/src\/cmd\/compile\/internal\/types\/type.go#L390-L394\"><code>src\/cmd\/compile\/internal\/types\/type.go<\/code><\/a>\uff09\u306b\u4fdd\u6301\u3055\u308c\u3066\u304a\u308a\u3001<code>NumElem()<\/code>\u30e1\u30bd\u30c3\u30c9(<a target=\"_blank\" href=\"https:\/\/github.com\/golang\/go\/blob\/master\/src\/cmd\/compile\/internal\/types\/type.go#L1475-L1478\"><code>src\/cmd\/compile\/internal\/types\/type.go<\/code><\/a>)\u3067\u53d6\u5f97\u53ef\u80fd\u3067\u3059\u3002Fig. 8\u306bGo\u30b3\u30f3\u30d1\u30a4\u30e9\u5185\u90e8\u306e\u914d\u5217\u578b\u5b9a\u7fa9\u306e\u629c\u7c8b\u3092\u793a\u3057\u307e\u3059\u3002<\/p>\n<pre class=\"code lang-go\" data-lang=\"go\" data-unlink=\"\">\n<span class=\"synStatement\">type<\/span> Array <span class=\"synStatement\">struct<\/span> {\n    Elem  *Type \n    Bound <span class=\"synType\">int64<\/span> <\/pre>\n<p><em>Fig. 8. \u914d\u5217\u578b<code>Array<\/code>\u306e\u5b9a\u7fa9\u3068\u9577\u3055\u3092\u8fd4\u3059<code>NumElem<\/code>\u30e1\u30bd\u30c3\u30c9<\/em><\/p>\n<p>\u3053\u306e\u3088\u3046\u306b\u3057\u3066\u30b3\u30f3\u30d1\u30a4\u30e9\u306f\u914d\u5217\u9577\u3092\u53d6\u5f97\u3057\u307e\u3059\u3002\u7d50\u679c\u3068\u3057\u3066\u3001<strong>\u914d\u5217\u306e<code>len<\/code>\u547c\u3073\u51fa\u3057\u306f\u5358\u306a\u308b\u5b9a\u6570\u53c2\u7167<\/strong>\u3068\u306a\u308a\u3001\u30e9\u30f3\u30bf\u30a4\u30e0\u30b3\u30b9\u30c8\u306f\u30bc\u30ed\u3067\u3059\u3002<\/p>\n<h3 id=\"\u30b9\u30e9\u30a4\u30b9\u306b\u5bfe\u3059\u308blen\">\u30b9\u30e9\u30a4\u30b9\u306b\u5bfe\u3059\u308b<code>len<\/code><\/h3>\n<p>\u30b9\u30e9\u30a4\u30b9\uff08<code>[]T<\/code>\uff09\u306f\u53ef\u5909\u9577\u306e\u30b7\u30fc\u30b1\u30f3\u30b9\u3092\u8868\u3059\u69cb\u9020\u4f53\u3067\u3001\u5185\u90e8\u7684\u306b\u306f\u30dd\u30a4\u30f3\u30bf\uff08\u914d\u5217\u30c7\u30fc\u30bf\u3078\u306e\u53c2\u7167\uff09\u3001\u9577\u3055<code>Len<\/code>\u3001\u5bb9\u91cf<code>Cap<\/code>\u306e3\u3064\u306e\u30d5\u30a3\u30fc\u30eb\u30c9\u304b\u3089\u69cb\u6210\u3055\u308c\u3066\u3044\u307e\u3059\u3002Go\u306e\u6a19\u6e96\u30d1\u30c3\u30b1\u30fc\u30b8<code>reflect<\/code>\u3067\u306f\u4ee5\u4e0b\u306e\u3088\u3046\u306b\u5b9a\u7fa9\u3055\u308c\u3066\u3044\u307e\u3059(<a target=\"_blank\" href=\"https:\/\/github.com\/golang\/go\/blob\/master\/src\/reflect\/value.go#L2644-L2648\"><code>src\/reflect\/value.go<\/code><\/a>)\u3002<\/p>\n<pre class=\"code lang-go\" data-lang=\"go\" data-unlink=\"\"><span class=\"synStatement\">type<\/span> SliceHeader <span class=\"synStatement\">struct<\/span> {\n    Data <span class=\"synType\">uintptr<\/span>\n    Len  <span class=\"synType\">int<\/span>\n    Cap  <span class=\"synType\">int<\/span>\n}\n<\/pre>\n<p><em>Fig. 9. \u30b9\u30e9\u30a4\u30b9\u306e\u5185\u90e8\u69cb\u9020\u4f53<code>SliceHeader<\/code><\/em><\/p>\n<p>\u30b9\u30e9\u30a4\u30b9\u306b\u5bfe\u3059\u308b<code>len(s)<\/code>\u306f\u3001\u3053\u306e\u69cb\u9020\u4f53\u306e<code>Len<\/code>\u30d5\u30a3\u30fc\u30eb\u30c9\u306e\u5024\u3092\u8fd4\u3057\u307e\u3059\u3002\u30b3\u30f3\u30d1\u30a4\u30eb\u5f8c\u306e\u6a5f\u68b0\u8a9e\u3067\u306f\u3001\u30b9\u30e9\u30a4\u30b9\u306e\u9577\u3055\u53d6\u5f97\u306f<strong>\u5bfe\u5fdc\u3059\u308b\u30d5\u30a3\u30fc\u30eb\u30c9\u3092\u8aad\u307f\u51fa\u3059\u3060\u3051<\/strong>\u306e\u64cd\u4f5c\u306b\u306a\u308a\u307e\u3059\u3002\u4f8b\u3048\u3070x86-64\u306e\u5834\u5408\u3001\u30b9\u30e9\u30a4\u30b9\u304c\u30ec\u30b8\u30b9\u30bf\u3084\u30b9\u30bf\u30c3\u30af\u4e0a\u306b\u8f09\u3063\u3066\u3044\u308c\u3070\u3001\u305d\u306e<code>Len<\/code>\u90e8\u5206\u3092MOV\u547d\u4ee4\u3067\u8aad\u307f\u8fbc\u3080\u3060\u3051\u3067\u6e08\u307f\u307e\u3059\u3002<\/p>\n<p>\u30b3\u30f3\u30d1\u30a4\u30e9\u306fSSA\u547d\u4ee4<code>OpSliceLen<\/code>\u3067\u30b9\u30e9\u30a4\u30b9\u9577\u53d6\u5f97\u3092\u8868\u3057\u3001\u6700\u7d42\u7684\u306a\u30b3\u30fc\u30c9\u751f\u6210\u6642\u306b\u305d\u308c\u3092\u9069\u5207\u306a\u30aa\u30d5\u30bb\u30c3\u30c8\u306e\u8aad\u307f\u51fa\u3057\u547d\u4ee4\u306b\u7f6e\u304d\u63db\u3048\u307e\u3059\u3002\u3059\u3067\u306b\u8ff0\u3079\u305f\u901a\u308a\u3001<code>Len<\/code>\u30d5\u30a3\u30fc\u30eb\u30c9\u306f\u69cb\u9020\u4f53\u5148\u982d\u306e\u30dd\u30a4\u30f3\u30bf\u306e\u76f4\u5f8c\u306b\u4f4d\u7f6e\u3059\u308b\u305f\u3081\u3001\u30dd\u30a4\u30f3\u30bf\u306e\u30b5\u30a4\u30ba\u5206\u30aa\u30d5\u30bb\u30c3\u30c8\u3057\u305f\u30e1\u30e2\u30ea\u30a2\u30c9\u30ec\u30b9\u304b\u3089<code>int<\/code>\u5024\u3092\u8aad\u307f\u53d6\u308c\u3070<code>len<\/code>\u304c\u5f97\u3089\u308c\u307e\u3059\u3002\u30b3\u30f3\u30d1\u30a4\u30e9\u306f\u3053\u306e<code>offset<\/code>\u8a08\u7b97\u3068\u8aad\u307f\u51fa\u3057\u3092\u81ea\u52d5\u7684\u306b\u884c\u3044\u307e\u3059\u3002<\/p>\n<p><strong><code>nil<\/code>\u30b9\u30e9\u30a4\u30b9<\/strong>\u306e\u5834\u5408\u3067\u3082\u3001\u5185\u90e8\u8868\u73fe\u4e0a\u306f<code>Data=nil, Len=0, Cap=0<\/code>\u3068\u3044\u3046\u69cb\u9020\u4f53\u5024\u306b\u306a\u3063\u3066\u3044\u307e\u3059\u3002\u3057\u305f\u304c\u3063\u3066<code>len(nilSlice)<\/code>\u3082\u30e1\u30e2\u30ea\u4e0a0\u3092\u8aad\u307f\u53d6\u308b\u3060\u3051\u3067\u3001\u7279\u5225\u306a\u5206\u5c90\u306a\u3057\u306b0\u304c\u5f97\u3089\u308c\u307e\u3059\u3002\u30b9\u30e9\u30a4\u30b9\u306b\u95a2\u3057\u3066\u306f\u3001<code>nil<\/code>\u3067\u3042\u3063\u3066\u3082\u9577\u3055\u30d5\u30a3\u30fc\u30eb\u30c9\u306f\u5e38\u306b0\u306b\u30bb\u30c3\u30c8\u3055\u308c\u3066\u3044\u308b\u305f\u3081\u3001<strong>\u4f59\u5206\u306a<code>nil<\/code>\u30c1\u30a7\u30c3\u30af\u306f\u4e0d\u8981<\/strong>\u3068\u3044\u3046\u70b9\u304c\u30de\u30c3\u30d7\/\u30c1\u30e3\u30cd\u30eb\u3068\u306f\u7570\u306a\u308a\u307e\u3059\u3002\u3053\u306e\u305f\u3081\u3001\u4f8b\u3048\u3070\u95a2\u6570\u306e\u5f15\u6570\u3067\u30b9\u30e9\u30a4\u30b9\u3092\u53d7\u3051\u53d6\u308b\u5834\u5408\u3001\u30b3\u30f3\u30d1\u30a4\u30e9\u306f<code>nil<\/code>\u304b\u3069\u3046\u304b\u306b\u95a2\u308f\u3089\u305a\u5358\u4e00\u306e\u547d\u4ee4\u3067\u9577\u3055\u3092\u53d6\u5f97\u3059\u308b\u30b3\u30fc\u30c9\u3092\u751f\u6210\u3057\u307e\u3059\u3002<\/p>\n<h3 id=\"\u6587\u5b57\u5217\u306b\u5bfe\u3059\u308blen\">\u6587\u5b57\u5217\u306b\u5bfe\u3059\u308b<code>len<\/code><\/h3>\n<p>\u6587\u5b57\u5217\uff08<code>string<\/code>\uff09\u306f\u4e0d\u5909\u306e\u30d0\u30a4\u30c8\u5217\u3092\u8868\u3059\u578b\u3067\u3001\u5185\u90e8\u7684\u306b\u306f\u30c7\u30fc\u30bf\u3078\u306e\u30dd\u30a4\u30f3\u30bf\u3068\u9577\u3055\u3092\u6301\u3064\u70b9\u3067\u30b9\u30e9\u30a4\u30b9\u306b\u4f3c\u3066\u3044\u307e\u3059\uff08\u5bb9\u91cf\u304c\u306a\u3044\u3076\u3093\u30b9\u30e9\u30a4\u30b9\u3088\u308a\u30d5\u30a3\u30fc\u30eb\u30c9\u304c\u4e00\u3064\u5c11\u306a\u3044\u69cb\u9020\u4f53\u3067\u3059\uff09\u3002<code>len(str)<\/code>\u306f<strong>\u6587\u5b57\u5217\u306e\u30d0\u30a4\u30c8\u6570<\/strong>\uff08\u30e1\u30e2\u30ea\u4e0a\u306e\u9577\u3055\uff09\u3092\u8fd4\u3057\u307e\u3059\u3002\u3053\u3061\u3089\u3082\u5b9f\u884c\u6642\u306b\u306f\u6587\u5b57\u5217\u69cb\u9020\u4f53\u306e\u9577\u3055\u30d5\u30a3\u30fc\u30eb\u30c9\u3092\u8aad\u307f\u53d6\u308b\u3060\u3051\u3067\u3001\u30b9\u30e9\u30a4\u30b9\u540c\u69d8\u306b1\u547d\u4ee4\u3067\u53d6\u5f97\u53ef\u80fd\u3067\u3059\u3002<\/p>\n<p>\u6587\u5b57\u5217\u306f<code>nil<\/code>\u3068\u3044\u3046\u5024\u306f\u5b58\u5728\u3057\u307e\u305b\u3093\uff08\u7a7a\u6587\u5b57\u5217&#8221;&#8221;\u306f<code>Len=0<\/code>\u3067\u3059\u304c<code>Data<\/code>\u30d5\u30a3\u30fc\u30eb\u30c9\u306f\u30b9\u30e9\u30a4\u30b9\u3068\u306f\u7570\u306a\u308a\u30bc\u30ed\u3067\u306f\u306a\u3044\u53ef\u80fd\u6027\u304c\u3042\u308a\u307e\u3059\uff09\u3002\u3057\u304b\u3057\u8a00\u8a9e\u4ed5\u69d8\u4e0a\u3001\u6587\u5b57\u5217\u306f\u30bc\u30ed\u5024\u3067\u306f<code>Data<\/code>\u30d5\u30a3\u30fc\u30eb\u30c9\u304c\u7279\u5b9a\u306e<code>nil<\/code>\u3067\u306f\u306a\u304f<strong>\u5225\u306e\u7279\u6b8a\u306a\u5834\u6240<\/strong>\u3092\u6307\u3057\u3066\u3044\u308b\u5b9f\u88c5\u306b\u306a\u3063\u3066\u3044\u307e\u3059\u304c\u3001\u9577\u3055\u306f0\u3068\u306a\u3063\u3066\u3044\u307e\u3059\u3002\u305d\u306e\u305f\u3081<code>len(\"\")<\/code>\u306f0\u3092\u8fd4\u3057\u3001\u305d\u306e\u4ed6\u306e\u5834\u5408\u3082\u683c\u7d0d\u3055\u308c\u305f\u30d0\u30a4\u30c8\u6570\u3092\u8fd4\u3057\u307e\u3059\u3002<\/p>\n<h3 id=\"\u30de\u30c3\u30d7\u306b\u5bfe\u3059\u308blen\">\u30de\u30c3\u30d7\u306b\u5bfe\u3059\u308b<code>len<\/code><\/h3>\n<p>\u30de\u30c3\u30d7\uff08<code>map[K]V<\/code>\uff09\u306f\u53c2\u7167\u578b\u3067\u3001\u5185\u90e8\u7684\u306b\u306f\u30cf\u30c3\u30b7\u30e5\u30de\u30c3\u30d7\u69cb\u9020\u4f53\uff08<code>runtime.hmap<\/code>\u578b\uff09\u306e\u30dd\u30a4\u30f3\u30bf\u3068\u3057\u3066\u5b9f\u88c5\u3055\u308c\u3066\u3044\u307e\u3059\u3002<code>len(m)<\/code>\u306f\u30de\u30c3\u30d7\u306e\u8981\u7d20\u6570\uff08\u30a8\u30f3\u30c8\u30ea\u6570\uff09\u3092\u8fd4\u3057\u307e\u3059\u3002\u30e9\u30f3\u30bf\u30a4\u30e0\u306e<code>hmap<\/code>\u69cb\u9020\u4f53\u5b9a\u7fa9\u3092\u898b\u308b\u3068\u3001\u5148\u982d\u306b<code>count<\/code>\u3068\u3044\u3046\u30d5\u30a3\u30fc\u30eb\u30c9\u304c\u3042\u308a\u3001\u305d\u3053\u306b\u73fe\u5728\u306e\u8981\u7d20\u6570\u304c\u4fdd\u6301\u3055\u308c\u3066\u3044\u307e\u3059\u3002\u4ee5\u4e0b\u306b\u305d\u306e\u4e00\u90e8\u3092\u793a\u3057\u307e\u3059(<a target=\"_blank\" href=\"https:\/\/go.dev\/src\/runtime\/map_noswiss.go\"><code>src\/runtime\/map_noswiss.go<\/code><\/a>)\u3002<\/p>\n<pre class=\"code lang-go\" data-lang=\"go\" data-unlink=\"\"><span class=\"synStatement\">type<\/span> hmap <span class=\"synStatement\">struct<\/span> {\n    count     <span class=\"synType\">int<\/span> \n    flags     <span class=\"synType\">uint8<\/span>\n    B         <span class=\"synType\">uint8<\/span>\n    noverflow <span class=\"synType\">uint16<\/span>\n    hash0     <span class=\"synType\">uint32<\/span>\n    buckets    <span class=\"synType\">unsafe.Pointer<\/span>\n    ...\n}\n<\/pre>\n<p><em>Fig. 10. \u30de\u30c3\u30d7\u306e\u5185\u90e8\u69cb\u9020\u4f53<code>hmap<\/code>\uff08\u5148\u982d\u306e<code>count<\/code>\u306b\u8981\u7d20\u6570\u3092\u4fdd\u6301\uff09<\/em><\/p>\n<p>\u3053\u306e<code>count<\/code>\u3053\u305d\u304c<code>len<\/code>\u306e\u8fd4\u3059\u5024\u3067\u3059\u3002\u30b3\u30f3\u30d1\u30a4\u30eb\u5f8c\u306e\u30b3\u30fc\u30c9\u3067\u306f\u3001\u30de\u30c3\u30d7\u306e\u30dd\u30a4\u30f3\u30bf\uff08<code>*hmap<\/code>\uff09\u304c\u30ec\u30b8\u30b9\u30bf\u306a\u308a\u30e1\u30e2\u30ea\u306a\u308a\u306b\u3042\u308b\u3068\u3057\u3066\u3001\u305d\u306e\u30a2\u30c9\u30ec\u30b9\u306b\u5bfe\u3057\u3066<strong>\u5148\u982d\u306e<code>int<\/code>\u5024\u3092\u8aad\u307f\u51fa\u3059<\/strong>\u51e6\u7406\u306b\u306a\u308a\u307e\u3059\u3002\u4f8b\u3048\u3070x86-64\u3067\u306f\u3001\u30de\u30c3\u30d7\u30dd\u30a4\u30f3\u30bf\u304c\u30ec\u30b8\u30b9\u30bfRDI\u306b\u5165\u3063\u3066\u3044\u308b\u5834\u5408\u3001<code>MOVQ (RDI), AX<\/code>\u306e\u3088\u3046\u306a\u547d\u4ee4\u3067\u5148\u982d8\u30d0\u30a4\u30c8\uff0864\u30d3\u30c3\u30c8\uff09\u306e<code>count<\/code>\u3092AX\u30ec\u30b8\u30b9\u30bf\u306b\u8aad\u307f\u8fbc\u307f\u3001\u305d\u308c\u3092\u8fd4\u308a\u5024\u3068\u3059\u308b\u3001\u3068\u3044\u3063\u305f\u30b3\u30fc\u30c9\u306b\u306a\u308a\u307e\u3059\u3002<\/p>\n<p>\u3057\u304b\u3057\u30de\u30c3\u30d7\u306e\u5834\u5408\u3001\u30b9\u30e9\u30a4\u30b9\u3068\u9055\u3044<strong>\u30dd\u30a4\u30f3\u30bf\u304c<code>nil<\/code>\u3067\u3042\u308b\u53ef\u80fd\u6027<\/strong>\u304c\u3042\u308a\u307e\u3059\u3002<code>nil<\/code>\u30de\u30c3\u30d7\u306f\u8981\u7d20\u65700\u3068\u5b9a\u7fa9\u3055\u308c\u3066\u3044\u308b\u305f\u3081\u3001<code>nil<\/code>\u3092\u6271\u3046\u969b\u306f0\u3092\u8fd4\u3055\u306d\u3070\u306a\u308a\u307e\u305b\u3093\u3002<code>nil<\/code>\u30dd\u30a4\u30f3\u30bf\u306e\u307e\u307e\u5148\u982d\u3092\u8aad\u307f\u306b\u884c\u3051\u3070\u30e1\u30e2\u30ea\u30a2\u30af\u30bb\u30b9\u9055\u53cd\u306b\u306a\u308b\u305f\u3081\u3001\u30b3\u30f3\u30d1\u30a4\u30e9\u306f\u4e8b\u524d\u306b<code>nil<\/code>\u304b\u3069\u3046\u304b\u30c1\u30a7\u30c3\u30af\u3059\u308b\u30b3\u30fc\u30c9\u3092\u751f\u6210\u3057\u307e\u3059\uff08Fig. 6\u53c2\u7167\uff09\u3002\u5b9f\u969b\u306e\u30a2\u30bb\u30f3\u30d6\u30ea\u3067\u306f\u3001<code>CMPQ RDI, $0<\/code>\uff08\u30de\u30c3\u30d7\u30dd\u30a4\u30f3\u30bf\u304c0\u304b\u6bd4\u8f03\uff09\u3068\u3044\u3063\u305f\u547d\u4ee4\u3067<code>nil<\/code>\u5224\u5b9a\u3057\u3001\u30bc\u30ed\u306a\u3089\u9577\u30550\u3092\u30bb\u30c3\u30c8\u3057\u3066\u7d42\u4e86\u3001\u305d\u308c\u4ee5\u5916\u306a\u3089<code>MOVQ (RDI), AX<\/code>\u3067<code>count<\/code>\u3092\u8aad\u307f\u8fbc\u3080\u3001\u3068\u3044\u3063\u305f\u5206\u5c90\u306b\u306a\u308a\u307e\u3059\u3002<\/p>\n<h3 id=\"\u30c1\u30e3\u30cd\u30eb\u306b\u5bfe\u3059\u308blen\">\u30c1\u30e3\u30cd\u30eb\u306b\u5bfe\u3059\u308b<code>len<\/code><\/h3>\n<p>\u30c1\u30e3\u30cd\u30eb\uff08<code>chan T<\/code>\uff09\u3082\u53c2\u7167\u578b\u3067\u3001\u5185\u90e8\u7684\u306b\u306f\u53cc\u65b9\u5411\u30ad\u30e5\u30fc\u69cb\u9020<code>runtime.hchan<\/code>\u306e\u30dd\u30a4\u30f3\u30bf\u3067\u8868\u73fe\u3055\u308c\u3066\u3044\u307e\u3059\u3002<code>len(ch)<\/code>\u306f\u30c1\u30e3\u30cd\u30eb\u30d0\u30c3\u30d5\u30a1\u306b\u84c4\u7a4d\u3057\u3066\u3044\u308b\u8981\u7d20\u306e\u500b\u6570\u3092\u8fd4\u3057\u307e\u3059\u3002\u30e9\u30f3\u30bf\u30a4\u30e0\u306e<code>hchan<\/code>\u5b9a\u7fa9\u3067\u306f\u5148\u982d\u306b<code>qcount<\/code>\u3068\u3044\u3046<code>uint<\/code>\u5024\u304c\u3042\u308a\u3001\u3053\u308c\u304c\u73fe\u5728\u306e\u30d0\u30c3\u30d5\u30a1\u5185\u30c7\u30fc\u30bf\u6570\u3092\u4fdd\u6301\u3057\u3066\u3044\u307e\u3059(<a target=\"_blank\" href=\"https:\/\/github.com\/golang\/go\/blob\/master\/src\/runtime\/chan.go#L34-L55\"><code>src\/runtime\/chan.go<\/code><\/a>)\u3002<\/p>\n<pre class=\"code lang-go\" data-lang=\"go\" data-unlink=\"\"><span class=\"synStatement\">type<\/span> hchan <span class=\"synStatement\">struct<\/span> {\n    qcount   <span class=\"synType\">uint<\/span>           \n    dataqsiz <span class=\"synType\">uint<\/span>\n    buf      <span class=\"synType\">unsafe.Pointer<\/span>\n    elemsize <span class=\"synType\">uint16<\/span>\n    closed   <span class=\"synType\">uint32<\/span>\n    elemtype *_type\n    ...\n}\n<\/pre>\n<p><em>Fig. 11. \u30c1\u30e3\u30cd\u30eb\u306e\u5185\u90e8\u69cb\u9020\u4f53<code>hchan<\/code>\uff08\u5148\u982d\u306e<code>qcount<\/code>\u306b\u30ad\u30e5\u30fc\u5185\u8981\u7d20\u6570\u3092\u4fdd\u6301\uff09<\/em><\/p>\n<p>\u3053\u306e<code>qcount<\/code>\u304c<code>len(chan)<\/code>\u306e\u8fd4\u308a\u5024\u306b\u306a\u308a\u307e\u3059\u3002\u5b9f\u88c5\u4e0a\u306f\u30de\u30c3\u30d7\u3068\u540c\u69d8\u3001\u30c1\u30e3\u30cd\u30eb\u30dd\u30a4\u30f3\u30bf\u306e\u5148\u982d\u30ef\u30fc\u30c9\u3092\u8aad\u307f\u51fa\u3059\u3060\u3051\u3067\u3059\u3002\u305f\u3060\u3057\u30c1\u30e3\u30cd\u30eb\u3082<code>nil<\/code>\u30dd\u30a4\u30f3\u30bf\u306e\u53ef\u80fd\u6027\u304c\u3042\u308b\u305f\u3081\u3001\u3084\u306f\u308a<strong><code>nil<\/code>\u30c1\u30a7\u30c3\u30af\u3092\u542b\u3080\u30b3\u30fc\u30c9<\/strong>\u306b\u306a\u308a\u307e\u3059\u3002<code>nil<\/code>\u30c1\u30e3\u30cd\u30eb\u306f\u9577\u30550\u3068\u5b9a\u7fa9\u3055\u308c\u3066\u3044\u307e\u3059\u306e\u3067\u3001<code>nil<\/code>\u3067\u3042\u308c\u30700\u3092\u8fd4\u3059\u3088\u3046\u5206\u5c90\u3057\u307e\u3059\u3002\u975e<code>nil<\/code>\u306a\u3089<code>qcount<\/code>\u3092\u8aad\u307f\u53d6\u308a\u307e\u3059\u3002<\/p>\n<h2 id=\"SSA\u304b\u3089\u6700\u7d42\u30a2\u30bb\u30f3\u30d6\u30ea\u3078\u306e\u5909\u63db\u4f8b\">SSA\u304b\u3089\u6700\u7d42\u30a2\u30bb\u30f3\u30d6\u30ea\u3078\u306e\u5909\u63db\u4f8b<\/h2>\n<p>\u6700\u5f8c\u306b\u3001\u5b9f\u969b\u306e\u30a2\u30bb\u30f3\u30d6\u30ea\u30b3\u30fc\u30c9\u4e0a\u3067<code>len<\/code>\u304c\u3069\u306e\u3088\u3046\u306b\u306a\u308b\u304b\u3001\u7c21\u5358\u306a\u4f8b\u3092\u793a\u3057\u307e\u3059\u3002\u4ee5\u4e0b\u306b\u30b9\u30e9\u30a4\u30b9\u3068\u30de\u30c3\u30d7\u306e<code>len<\/code>\u3092\u8fd4\u3059\u95a2\u6570\u3092\u60f3\u5b9a\u3057\u3001x86-64\u30a2\u30bb\u30f3\u30d6\u30ea\u51fa\u529b\u3092\u4f8b\u793a\u3057\u307e\u3059\u3002<\/p>\n<pre class=\"code lang-asm\" data-lang=\"asm\" data-unlink=\"\">\n<span class=\"synStatement\">lenSlice<\/span>:\n    <span class=\"synIdentifier\">MOVQ<\/span>    <span class=\"synIdentifier\">RSI<\/span>, <span class=\"synIdentifier\">AX<\/span>        \n    <span class=\"synIdentifier\">RET<\/span>                    \n\n\n<span class=\"synStatement\">lenMap<\/span>:\n    <span class=\"synIdentifier\">CMPQ<\/span>    <span class=\"synIdentifier\">RDI<\/span>, $<span class=\"synConstant\">0<\/span>        \n    <span class=\"synIdentifier\">JEQ<\/span>     <span class=\"synStatement\">.Lnil<\/span>          \n    <span class=\"synIdentifier\">MOVQ<\/span>    (<span class=\"synIdentifier\">RDI<\/span>), <span class=\"synIdentifier\">AX<\/span>      \n    <span class=\"synIdentifier\">RET<\/span>\n<span class=\"synStatement\">.Lnil<\/span>:\n    <span class=\"synIdentifier\">XORL<\/span>    <span class=\"synIdentifier\">AX<\/span>, <span class=\"synIdentifier\">AX<\/span>         \n    <span class=\"synIdentifier\">RET<\/span>\n<\/pre>\n<p><em>Fig. 12. <code>len<\/code>\u306e\u30a2\u30bb\u30f3\u30d6\u30ea\u51fa\u529b\u4f8b\uff08\u30b9\u30e9\u30a4\u30b9\u306e\u5834\u5408\u306f1\u547d\u4ee4\u3001\u30de\u30c3\u30d7\u306e\u5834\u5408\u306f<code>nil<\/code>\u30c1\u30a7\u30c3\u30af\uff0b\u8aad\u307f\u53d6\u308a\uff09<\/em><\/p>\n<p>\u4e0a\u8a18\u306e\u3088\u3046\u306b\u3001\u30b9\u30e9\u30a4\u30b9\u9577\u53d6\u5f97\u306f<code>Len<\/code>\u30d5\u30a3\u30fc\u30eb\u30c9\u304c\u4fdd\u6301\u3055\u308c\u3066\u3044\u308b\u30ec\u30b8\u30b9\u30bf\uff08\u3053\u3053\u3067\u306f\u95a2\u6570\u547c\u51fa\u898f\u7d04\u4e0aRSI\u306b\u683c\u7d0d\uff09\u304b\u3089\u305d\u306e\u307e\u307eAX\u3078\u30b3\u30d4\u30fc\u3059\u308b\u3060\u3051\u3067\u5b8c\u4e86\u3057\u3066\u3044\u307e\u3059\u3002\u4e00\u65b9\u3001\u30de\u30c3\u30d7\u9577\u53d6\u5f97\u3067\u306fRDI\u30ec\u30b8\u30b9\u30bf\u306b\u30de\u30c3\u30d7\u306e\u30dd\u30a4\u30f3\u30bf\u304c\u6e21\u3055\u308c\u3066\u304a\u308a\u3001\u307e\u305a\u305d\u308c\u304c\u30bc\u30ed\u304b\u3069\u3046\u304b\u6bd4\u8f03\u3057\u305f\u5f8c\u3001\u30bc\u30ed\u3067\u306a\u3051\u308c\u3070\u30e1\u30e2\u30ea\u30a2\u30c9\u30ec\u30b9RDI\u304c\u6307\u3059\u5148\u306e\u5024\uff08<code>count<\/code>\uff09\u3092\u8aad\u307f\u53d6\u3063\u3066\u3044\u307e\u3059\u3002<code>nil<\/code>\u306e\u5834\u5408\u306f\u30b8\u30e3\u30f3\u30d7\u3057\u3066AX\u30ec\u30b8\u30b9\u30bf\u3092\u30bc\u30ed\u30af\u30ea\u30a2\u3059\u308b\u3053\u3068\u30670\u3092\u8a2d\u5b9a\u3057\u3001\u30ea\u30bf\u30fc\u30f3\u3057\u3066\u3044\u307e\u3059\u3002<\/p>\n<p>\u3053\u306e\u3088\u3046\u306b\u3001\u5b9f\u884c\u6642\u30b3\u30fc\u30c9\u306b\u304a\u3044\u3066<code>len<\/code>\u306f\u975e\u5e38\u306b\u4f4e\u30b3\u30b9\u30c8\u306a\u64cd\u4f5c\u3067\u3059\u3002\u5b9f\u969b\u3001<strong>\u30b9\u30e9\u30a4\u30b9\u3084\u6587\u5b57\u5217\u306e<code>len<\/code>\u53d6\u5f97\u306f\u30aa\u30fc\u30d0\u30fc\u30d8\u30c3\u30c9\u306e\u306a\u3044\u5358\u306a\u308b\u30e1\u30e2\u30ea\u53c2\u7167<\/strong>\u3068\u306a\u308a\u3001<strong>\u30de\u30c3\u30d7\u3084\u30c1\u30e3\u30cd\u30eb\u3067\u3082<code>nil<\/code>\u5224\u5b9a\uff0b\u30e1\u30e2\u30ea\u53c2\u7167\u7a0b\u5ea6<\/strong>\u306b\u5c55\u958b\u3055\u308c\u307e\u3059\u3002\u3053\u306e\u6700\u9069\u5316\u3055\u308c\u305f\u751f\u6210\u306b\u3088\u308a\u3001\u4f8b\u3048\u3070\u30eb\u30fc\u30d7\u306e\u7d42\u4e86\u6761\u4ef6\u306b<code>len(slice)<\/code>\u3092\u6bce\u56de\u66f8\u3044\u3066\u3082\u554f\u984c\u306a\u3044\uff08\u81ea\u660e\u306a\u30a4\u30f3\u30e9\u30a4\u30f3\u5c55\u958b\u306a\u306e\u3067\uff09\u306e\u306f\u3053\u306e\u305f\u3081\u3067\u3059\u3002<\/p>\n<blockquote>\n<p>\u30b3\u30f3\u30d1\u30a4\u30e9\u306f\u5834\u5408\u306b\u3088\u3063\u3066\u306f\u3055\u3089\u306a\u308b\u6700\u9069\u5316\u3082\u884c\u3044\u307e\u3059\u3002\u4f8b\u3048\u3070\u30eb\u30fc\u30d7\u5185\u3067\u9577\u3055\u304c\u5909\u308f\u3089\u306a\u3044\u30b9\u30e9\u30a4\u30b9\u306b\u5bfe\u3057\u3066\u6bce\u56de<code>len<\/code>\u3092\u547c\u3093\u3067\u3044\u308b\u3068\u3001\u6700\u9069\u5316\u3067\u30eb\u30fc\u30d7\u524d\u306b\u4e00\u5ea6\u3060\u3051<code>len<\/code>\u3092\u8a08\u7b97\u3057\u30ec\u30b8\u30b9\u30bf\u306b\u4fdd\u6301\u3059\u308b\u3001\u3068\u3044\u3063\u305f\u3053\u3068\u3082\u884c\u308f\u308c\u307e\u3059\u3002\u307e\u305f\u3001\u30b3\u30f3\u30d1\u30a4\u30e9\u306f<code>range<\/code>\u30eb\u30fc\u30d7\u306e\u30b3\u30fc\u30c9\u751f\u6210\u6642\u306b\u3082\u5185\u90e8\u3067<code>len<\/code>\u3092\u4f7f\u3044\u307e\u3059\u304c\u3001\u3053\u308c\u3082\u4e00\u5b9a\u306e\u5834\u5408\u3067\u5b9a\u6570\u3068\u307f\u306a\u3057\u3066\u8a55\u4fa1\u3092\u7701\u7565\u3059\u308b\u6319\u52d5\u304c\u3042\u308a\u307e\u3059\u3002<\/p>\n<\/blockquote>\n<h2 id=\"\u307e\u3068\u3081-\u306a\u305clen\u306f\u6f14\u7b97\u5b50\u7684\u306b\u8a2d\u8a08\u3055\u308c\u3066\u3044\u308b\u306e\u304b\">\u307e\u3068\u3081: \u306a\u305c<code>len<\/code>\u306f\u6f14\u7b97\u5b50\u7684\u306b\u8a2d\u8a08\u3055\u308c\u3066\u3044\u308b\u306e\u304b<\/h2>\n<p>\u4ee5\u4e0a\u3092\u8e0f\u307e\u3048\u3001\u6700\u5f8c\u306b<code>len<\/code>\u304c\u300c\u95a2\u6570\u300d\u3067\u306f\u306a\u304f\u8a00\u8a9e\u7d44\u307f\u8fbc\u307f\u306e\u6f14\u7b97\u5b50\u306e\u3088\u3046\u306b\u8a2d\u8a08\u3055\u308c\u3066\u3044\u308b\u7406\u7531\u306b\u3064\u3044\u3066\u307e\u3068\u3081\u307e\u3059\u3002<\/p>\n<h3 id=\"1-\u591a\u69d8\u306a\u578b\u306b\u5bfe\u5fdc\u3059\u308b\u305f\u3081\">1. \u591a\u69d8\u306a\u578b\u306b\u5bfe\u5fdc\u3059\u308b\u305f\u3081<\/h3>\n<p><code>len<\/code>\u306f\u914d\u5217\u3001\u30b9\u30e9\u30a4\u30b9\u3001\u6587\u5b57\u5217\u3001\u30de\u30c3\u30d7\u3001\u30c1\u30e3\u30cd\u30eb\u3068\u3044\u3063\u305f\u8907\u6570\u306e\u7d44\u307f\u8fbc\u307f\u578b\u306b\u5bfe\u3057\u3066\u4f7f\u3048\u307e\u3059\u3002\u3082\u3057\u901a\u5e38\u306e\u95a2\u6570\u3068\u3057\u3066\u5b9a\u7fa9\u3057\u3088\u3046\u3068\u3059\u308b\u3068\u3001\u3053\u308c\u3089\u3059\u3079\u3066\u306e\u578b\u306b\u3064\u3044\u3066\u95a2\u6570\u3084\u30e1\u30bd\u30c3\u30c9\u3092\u7528\u610f\u3059\u308b\u5fc5\u8981\u304c\u3042\u308a\u7169\u96d1\u3067\u3059\u3002\u3057\u304b\u3057\u7d44\u307f\u8fbc\u307f\u95a2\u6570\u3068\u3057\u3066\u30b3\u30f3\u30d1\u30a4\u30e9\u304c\u7279\u5225\u6271\u3044\u3059\u308b\u3053\u3068\u3067\u3001\u7d71\u4e00\u3057\u305f\u540d\u524d<code>len<\/code>\u3067\u69d8\u3005\u306a\u578b\u306e\u300c\u9577\u3055\u300d\u3092\u53d6\u5f97\u3067\u304d\u308b\u3088\u3046\u306b\u306a\u3063\u3066\u3044\u307e\u3059\u3002\u30b8\u30a7\u30cd\u30ea\u30af\u30b9\u304c\u5c0e\u5165\u3055\u308c\u305f\u73fe\u5728\u3067\u3082\u3001<code>len<\/code>\u306f\u30d3\u30eb\u30c8\u30a4\u30f3\u306e\u307e\u307e\u3067\u3059\uff08\u578b\u30d1\u30e9\u30e1\u30fc\u30bfP\u306b\u5bfe\u3057\u3066<code>len(x)<\/code>\u304c\u4f7f\u3048\u308b\u306e\u306f\u3001\u305d\u306e\u578b\u96c6\u5408\u5185\u306e\u3059\u3079\u3066\u306e\u5177\u4f53\u578b\u306b\u3064\u3044\u3066<code>len<\/code>\u304c\u5b9a\u7fa9\u3055\u308c\u3066\u3044\u308b\u5fc5\u8981\u304c\u3042\u308b\u3001\u3068\u3044\u3046\u5f62\u3067\u8a00\u8a9e\u4ed5\u69d8\u306b\u7d44\u307f\u8fbc\u307e\u308c\u3066\u3044\u307e\u3059\uff09\u3002<\/p>\n<h3 id=\"2-\u52b9\u7387\u306e\u305f\u3081\">2. \u52b9\u7387\u306e\u305f\u3081<\/h3>\n<p>\u4e0a\u8ff0\u306e\u3068\u304a\u308a\u3001<code>len<\/code>\u306e\u5b9f\u88c5\u306f\u975e\u5e38\u306b\u52b9\u7387\u7684\u306b\u6700\u9069\u5316\u3055\u308c\u307e\u3059\u3002\u30b3\u30f3\u30d1\u30a4\u30eb\u6642\u306b\u5206\u304b\u308b\u9577\u3055\u306f\u5b9a\u6570\u5316\u3057\u3001\u5b9f\u884c\u6642\u306b\u5fc5\u8981\u306a\u5834\u5408\u3082\u5358\u306a\u308b\u30d5\u30a3\u30fc\u30eb\u30c9\u30a2\u30af\u30bb\u30b9\u3084\u8efd\u5fae\u306a\u5206\u5c90\u3067\u6e08\u307f\u307e\u3059\u3002\u3053\u308c\u306f\u30b3\u30f3\u30d1\u30a4\u30e9\u30ec\u30d9\u30eb\u3067<code>len<\/code>\u3092\u6f14\u7b97\u5b50\u7684\u306b\u6271\u3063\u3066\u3044\u308b\u304b\u3089\u3053\u305d\u53ef\u80fd\u3068\u306a\u308b\u6700\u9069\u5316\u3067\u3059\u3002\u901a\u5e38\u306e\u95a2\u6570\u547c\u3073\u51fa\u3057\u3067\u3042\u308c\u3070\u30a4\u30f3\u30e9\u30a4\u30f3\u5c55\u958b\u3084\u6700\u9069\u5316\u306e\u5236\u7d04\u304c\u751f\u3058\u3048\u307e\u3059\u304c\u3001<code>len<\/code>\u306f\u8a00\u8a9e\u30ec\u30d9\u30eb\u3067\u7279\u5225\u6271\u3044\u3055\u308c\u308b\u305f\u3081\u305d\u306e\u3088\u3046\u306a\u30aa\u30fc\u30d0\u30fc\u30d8\u30c3\u30c9\u304c\u3042\u308a\u307e\u305b\u3093\u3002<\/p>\n<h3 id=\"3-\u30b3\u30fc\u30c9\u306e\u7c21\u6f54\u3055\u3068\u5b89\u5168\u6027\">3. \u30b3\u30fc\u30c9\u306e\u7c21\u6f54\u3055\u3068\u5b89\u5168\u6027<\/h3>\n<p><code>len<\/code>\u3092\u7d44\u307f\u8fbc\u307f\u3068\u3059\u308b\u8a2d\u8a08\u306f\u3001\u8a00\u8a9e\u5229\u7528\u8005\u306b\u3068\u3063\u3066\u3082\u6271\u3044\u3084\u3059\u3055\u3068\u5b89\u5168\u6027\u306b\u3064\u306a\u304c\u3063\u3066\u3044\u307e\u3059\u3002\u4f8b\u3048\u3070<code>len<\/code>\u306f\u5b9a\u7fa9\u4e0apanic\u3092\u8d77\u3053\u3057\u5f97\u307e\u305b\u3093\uff08\u3069\u3093\u306a\u5f15\u6570\u3067\u30820\u4ee5\u4e0a\u306e\u6574\u6570\u3092\u8fd4\u3059\uff09\u3057\u3001<code>nil<\/code>\u3082\u5b89\u5168\u306b\u51e6\u7406\u3055\u308c\u307e\u3059\u3002\u4eee\u306b<code>len<\/code>\u304c\u901a\u5e38\u306e\u95a2\u6570\u3067\u3042\u3063\u305f\u5834\u5408\u3001<code>nil<\/code>\u53c2\u7167\u306e\u30c1\u30a7\u30c3\u30af\u3084\u7570\u5e38\u7cfb\u51e6\u7406\u3092\u30e6\u30fc\u30b6\u304c\u610f\u8b58\u3059\u308b\u5fc5\u8981\u304c\u3042\u3063\u305f\u304b\u3082\u3057\u308c\u307e\u305b\u3093\u304c\u3001\u73fe\u5728\u306e\u8a2d\u8a08\u3067\u306f\u305d\u3046\u3057\u305f\u5fc3\u914d\u306f\u4e0d\u8981\u3067\u3059\u3002\u307e\u305f\u3001\u30d3\u30eb\u30c8\u30a4\u30f3\u3067\u3042\u308b\u305f\u3081<strong>\u30e6\u30fc\u30b6\u306f<code>len<\/code>\u3092\u30aa\u30fc\u30d0\u30fc\u30e9\u30a4\u30c9\u3057\u305f\u308a\u5225\u306e\u610f\u5473\u306b\u4f7f\u3063\u305f\u308a\u3067\u304d\u307e\u305b\u3093<\/strong>\u3002\u3053\u308c\u306b\u3088\u308a\u3001\u5e38\u306b<code>len<\/code>\u3068\u3044\u3046\u8868\u8a18\u306f\u8a00\u8a9e\u4ed5\u69d8\u3069\u304a\u308a\u306e\u610f\u5473\u3092\u6301\u3061\u3001\u30b3\u30fc\u30c9\u306e\u53ef\u8aad\u6027\u30fb\u4e00\u8cab\u6027\u304c\u4fdd\u305f\u308c\u307e\u3059\u3002<\/p>\n<h3 id=\"4-\u5185\u90e8\u5b9f\u88c5\u306e\u30ab\u30d7\u30bb\u30eb\u5316\">4. \u5185\u90e8\u5b9f\u88c5\u306e\u30ab\u30d7\u30bb\u30eb\u5316<\/h3>\n<p><code>len<\/code>\u3092\u7d44\u307f\u8fbc\u307f\u95a2\u6570\u3068\u3057\u305f\u3053\u3068\u3067\u3001\u5404\u30c7\u30fc\u30bf\u69cb\u9020\u306e\u5185\u90e8\u5b9f\u88c5\uff08\u4f8b\u3048\u3070\u30de\u30c3\u30d7\u306e\u69cb\u9020\u4f53\u3084\u30c1\u30e3\u30cd\u30eb\u306e\u69cb\u9020\u4f53\uff09\u3092\u76f4\u63a5\u516c\u958b\u305b\u305a\u306b\u300c\u8981\u7d20\u6570\u300d\u3068\u3044\u3046\u60c5\u5831\u3060\u3051\u3092\u63d0\u4f9b\u3067\u304d\u307e\u3059\u3002\u30e6\u30fc\u30b6\u306f\u3053\u308c\u3089\u69cb\u9020\u306e\u8a73\u7d30\u3092\u6c17\u306b\u305b\u305a<code>len<\/code>\u3092\u4f7f\u3048\u307e\u3059\u3057\u3001\u4eee\u306b\u5c06\u6765\u5185\u90e8\u5b9f\u88c5\u304c\u5909\u308f\u3063\u3066\u3082<code>len<\/code>\u306e\u632f\u308b\u821e\u3044\u306f\u4fdd\u8a3c\u3055\u308c\u307e\u3059\u3002\u5b9f\u969b\u3001Go\u306e\u30e9\u30f3\u30bf\u30a4\u30e0\u5b9f\u88c5\u306f\u81ea\u7531\u306b\u5909\u66f4\u53ef\u80fd\u3067\u3059\u304c\u3001<code>len<\/code>\u306e\u7d50\u679c\u3060\u3051\u306f\u5e38\u306b\u6b63\u3057\u304f\u306a\u308b\u3088\u3046\u30b3\u30f3\u30d1\u30a4\u30e9\u3068\u30e9\u30f3\u30bf\u30a4\u30e0\u5074\u3067\u7d04\u675f\u3057\u3066\u3044\u307e\u3059\u3002<\/p>\n<p>\u4ee5\u4e0a\u306e\u7406\u7531\u304b\u3089\u3001Go\u306e<code>len<\/code>\u306f\u8a00\u8a9e\u30ec\u30d9\u30eb\u3067\u7279\u6b8a\u6271\u3044\u3055\u308c\u308b\u6f14\u7b97\u5b50\u7684\u306a\u7d44\u307f\u8fbc\u307f\u95a2\u6570\u3068\u3057\u3066\u8a2d\u8a08\u3055\u308c\u3066\u3044\u307e\u3059\u3002\u305d\u306e\u304a\u304b\u3052\u3067\u3001\u79c1\u305f\u3061\u306f<code>len<\/code>\u3092\u307e\u308b\u3067\u914d\u5217\u3084\u30b9\u30e9\u30a4\u30b9\u306a\u3069\u306b\u5bfe\u3059\u308b\u6f14\u7b97\u5b50\u306e\u3088\u3046\u306b<strong>\u3069\u3093\u306a\u5834\u9762\u3067\u3082\u5b89\u5fc3\u3057\u3066<\/strong>\u4f7f\u3046\u3053\u3068\u304c\u3067\u304d\u307e\u3059\u3002\u5b9f\u88c5\u4e0a\u3082\u7121\u99c4\u306a\u30b3\u30b9\u30c8\u304c\u306a\u304f\u3001<strong>\u300c\u9577\u3055\u3092\u6c42\u3081\u308b\u300d\u3068\u3044\u3046\u975e\u5e38\u306b\u57fa\u672c\u7684\u306a\u64cd\u4f5c\u3092\u9ad8\u901f\u304b\u3064\u5b89\u5168\u306b\u884c\u3046<\/strong>\u3053\u3068\u3092Go\u306f\u4fdd\u8a3c\u3057\u3066\u3044\u308b\u306e\u3067\u3059\u3002<\/p>\n<h2 id=\"\u304a\u308f\u308a\u306b\">\u304a\u308f\u308a\u306b<\/h2>\n<p>\u672c\u8a18\u4e8b\u3067\u306f\u3001Go\u306b\u304a\u3051\u308b\u57fa\u672c\u7684\u306a\u7d44\u307f\u8fbc\u307f\u95a2\u6570<code>len<\/code>\u306e\u5185\u90e8\u6319\u52d5\u306b\u3064\u3044\u3066\u307e\u3068\u3081\u3066\u307f\u307e\u3057\u305f\u3002\u666e\u6bb5\u4f55\u6c17\u306a\u304f\u4f7f\u3063\u3066\u3044\u308b\u95a2\u6570\u3067\u3059\u304c\u3001\u8abf\u3079\u3066\u3044\u304f\u3068\u77e5\u3089\u306a\u3044\u3053\u3068\u3070\u304b\u308a\u3067\u9a5a\u304d\u306e\u9023\u7d9a\u3067\u3057\u305f\u3002Go\u306b\u306f<code>len<\/code>\u306e\u4ed6\u306b\u3082\u3044\u304f\u3064\u304b\u540c\u69d8\u306e\u7d44\u307f\u8fbc\u307f\u95a2\u6570\uff08<code>cap<\/code>, <code>new<\/code>, <code>make<\/code>\u306a\u3069\uff09\u304c\u3042\u308a\u307e\u3059\u3002\u3053\u308c\u3089\u3082<code>len<\/code>\u3068\u540c\u3058\u304f\u30b3\u30f3\u30d1\u30a4\u30e9\u306e<code>Universe<\/code>\u30d6\u30ed\u30c3\u30af\u306b\u5b9a\u7fa9\u3055\u308c\u3001\u5185\u90e8\u3067\u7279\u5225\u306b\u51e6\u7406\u3055\u308c\u307e\u3059\u3002Go\u8a00\u8a9e\u306e\u516c\u5f0f\u30c9\u30ad\u30e5\u30e1\u30f3\u30c8\u3084\u5b9f\u88c5\u30b3\u30fc\u30c9\u3092\u8aad\u3080\u3053\u3068\u3067\u3001\u30d3\u30eb\u30c8\u30a4\u30f3\u304c\u3069\u306e\u3088\u3046\u306b\u6271\u308f\u308c\u3066\u3044\u308b\u304b\u3055\u3089\u306b\u7406\u89e3\u304c\u6df1\u307e\u308b\u3067\u3057\u3087\u3046\u3002\u672c\u8a18\u4e8b\u304c\u3001<code>len<\/code>\u3068\u3044\u3046\u8eab\u8fd1\u306a\u95a2\u6570\u306e\u80cc\u5f8c\u306b\u3042\u308b\u8a00\u8a9e\u4ed5\u69d8\u3068\u30b3\u30f3\u30d1\u30a4\u30e9\u6280\u8853\u306b\u3064\u3044\u3066\u7406\u89e3\u3092\u6df1\u3081\u308b\u4e00\u52a9\u306b\u306a\u308c\u3070\u5e78\u3044\u3067\u3059\u3002<\/p>\n<hr\/>\n<p><strong>\u53c2\u8003\u6587\u732e:<\/strong><\/p>\n<\/div>\n<p><script>(function(d, s, id) {\n  var js, fjs = d.getElementsByTagName(s)[0];\n  if (d.getElementById(id)) return;\n  js = d.createElement(s); js.id = id;\n  js.src = \"\/\/connect.facebook.net\/ja_JP\/sdk.js#xfbml=1&appId=719729204785177&version=v17.0\";\n  fjs.parentNode.insertBefore(js, fjs);\n}(document, 'script', 'facebook-jssdk'));<\/script><br \/>\n<br \/>\n<br \/><a href=\"https:\/\/tech.every.tv\/entry\/2025\/10\/07\/193652\">\u5143\u306e\u8a18\u4e8b\u3092\u78ba\u8a8d\u3059\u308b <\/a><\/p>\n","protected":false},"excerpt":{"rendered":"title \u306f\u3058\u3081\u306b \u3053\u3093\u306b\u3061\u306f\u3002\u30c7\u30ea\u30c3\u30b7\u30e5\u30ad\u30c3\u30c1\u30f3\u958b\u767a\u90e8\u3067\u30d0\u30c3\u30af\u30a8\u30f3\u30c9\u30a8\u30f3\u30b8\u30cb\u30a2\u3092\u3057\u3066\u3044\u308b\u9234\u6728\u3067\u3059\u3002 Go\u8a00\u8a9e\u306e\u7d44\u307f\u8fbc\u307f\u95a2\u6570len()\u306f\u3001\u4e00\u898b\u30b7\u30f3\u30d7\u30eb\u306b\u914d\u5217\u3084\u30b9\u30e9\u30a4\u30b9\u306a\u3069\u306e\u300c\u9577\u3055\u300d\u3092\u8fd4\u3059\u95a2\u6570\u3067\u3059\u304c\u3001\u305d\u306e\u5b9f\u88c5\u306f\u30b3\u30f3\u30d1\u30a4\u30e9 [&hellip;]","protected":false},"author":1,"featured_media":8506,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[4],"tags":[],"class_list":["post-8505","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-company-tec"],"acf":[],"yoast_head":"<!-- This site is optimized with the Yoast SEO plugin v27.6 - https:\/\/yoast.com\/product\/yoast-seo-wordpress\/ -->\n<title>Go\u306e\u7d44\u307f\u8fbc\u307f\u95a2\u6570 len() \u306b\u8a73\u3057\u304f\u306a\u308b - every Tech Blog - \u30dd\u30b1\u30b3\u30f3<\/title>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/tech.every.tv\/entry\/2025\/10\/07\/193652\" \/>\n<meta property=\"og:locale\" content=\"ja_JP\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"Go\u306e\u7d44\u307f\u8fbc\u307f\u95a2\u6570 len() \u306b\u8a73\u3057\u304f\u306a\u308b - every Tech Blog - \u30dd\u30b1\u30b3\u30f3\" \/>\n<meta property=\"og:description\" content=\"title \u306f\u3058\u3081\u306b \u3053\u3093\u306b\u3061\u306f\u3002\u30c7\u30ea\u30c3\u30b7\u30e5\u30ad\u30c3\u30c1\u30f3\u958b\u767a\u90e8\u3067\u30d0\u30c3\u30af\u30a8\u30f3\u30c9\u30a8\u30f3\u30b8\u30cb\u30a2\u3092\u3057\u3066\u3044\u308b\u9234\u6728\u3067\u3059\u3002 Go\u8a00\u8a9e\u306e\u7d44\u307f\u8fbc\u307f\u95a2\u6570len()\u306f\u3001\u4e00\u898b\u30b7\u30f3\u30d7\u30eb\u306b\u914d\u5217\u3084\u30b9\u30e9\u30a4\u30b9\u306a\u3069\u306e\u300c\u9577\u3055\u300d\u3092\u8fd4\u3059\u95a2\u6570\u3067\u3059\u304c\u3001\u305d\u306e\u5b9f\u88c5\u306f\u30b3\u30f3\u30d1\u30a4\u30e9 [&hellip;]\" \/>\n<meta property=\"og:url\" content=\"https:\/\/tech.every.tv\/entry\/2025\/10\/07\/193652\" \/>\n<meta property=\"og:site_name\" content=\"\u30dd\u30b1\u30b3\u30f3\" \/>\n<meta property=\"article:published_time\" content=\"2025-10-07T13:33:40+00:00\" \/>\n<meta property=\"og:image\" content=\"https:\/\/pokecon.jp\/job\/wp-content\/uploads\/2025\/10\/https3A2F2Fcdn-ak.f.st-hatena.com2Fimages2Ffotolife2FM2FMotoshi07112F202510072F202510071929.png\" \/>\n\t<meta property=\"og:image:width\" content=\"1300\" \/>\n\t<meta property=\"og:image:height\" content=\"731\" \/>\n\t<meta property=\"og:image:type\" content=\"image\/png\" \/>\n<meta name=\"author\" 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