web6047 - 2025年 3月

構文解析　一応完成

今年の１月１2日から何となくで始めた構文解析。

１カ月半ほどかけてようやく（一応）完成したので、バグ探しも兼ねて「デモンストレーション」してみます。

デモは１～４まであります。

デモ１

まずはごく簡単な HTML です。

解析結果。

Object にはそれぞれ [html] とか [kakko<>] とか名前（種類名）が付けられています。

Object が持つ子要素は配列に格納されており、親子の階層構造を成しています。

HTML 構造としての階層分けはしていません。

HTML のタグごとにオブジェクト化されています。

デモ２

次にこの HTML に JavaScript を追加します。

解析結果。

SCRIPT タグで囲まれた部分は、JavaScript として認識されており、「言語の中の別の言語」に対応しています。

『function と来たら引数エリアを示す () と、本体エリアを示す {} が続くだろう』というようなプログラムを書いています。

実際のプログラミング言語の実行においても、

ERROR: unexpected ～（～は期待されていない）

というエラーメッセージはよく見ると思います。

『コンパイラや構文解析などの「言語の処理」においては、どんな単語や記号が「期待される」、という動きは共通してあるんだな』と今回の構文解析を作っていて思いました。

デモ３

前回の記事で問題にしていた、

このピンクの部分は if( A ) にとっての単文であり、「どう認識させるか？」ということでした。

解析結果。

Object: [javascript] [0] Object: [ifStatement] [0] "if" [1] Object: [kakko()] [0] "(" [1] " A " [2] ")" [2] " " [3] Object: [ifStatement] [0] "if" [1] Object: [kakko()] [0] "(" [1] " B " [2] ")" [2] " test4" [3] Object: [kakko()] [0] "(" [1] ")" [4] ";" [5] " " [6] Object: [elseStatement] [0] "else" [1] " test5" [2] Object: [kakko()] [0] "(" [1] ")" [3] ";" [4] " " [5] Object: [elseStatement] [0] "else" [1] " test6" [2] Object: [kakko()] [0] "(" [1] ")" [3] ";"

if( A ) の階層の中に if( B ) があり、if( B ) に係る else 構文は if( B ) の階層に入っており、その後 if( A ) に係る else 構文が if( A ) の階層にて続いています。

このようにちゃんと正しく認識されています。

認識の方法としては、

• if の中に if が来る時などはオブジェクトの親子関係の「階層」を作成する。
• 単文の終了を意味する ; やブロックの閉じ } が来たときはどの親子階層が終了するのかを区別する。
• また else が来たときはどの親子階層の if に係るのかを区別する。

などの処理を行っています。

デモ４

「コンパイラがコンパイラを作る」というのはよく聞く話ですが、今回の構文解析でも「構文解析が自分自身を構文解析」することができます。

実力が試されるところです。

解析結果。

Object: [html] [0] Object: [kakko<>] [0] "<" [1] "!DOCTYPE html" [2] ">" [1] "\n" [2] Object: [kakko<>] [0] "<" [1] "html" [2] ">" [3] "\n" [4] Object: [kakko<>] [0] "<" [1] "head" [2] ">" [5] "\n"
（中略） [6] Object: [kakko<>] [0] "<" [1] "title" [2] ">" [7] Object: [kakko<>] [0] "<" [1] "/title" [2] ">" [8] "\n" [9] Object: [kakko<>] [0] "<" [1] "meta content=" [2] Object: [doubleQuote] [0] """ [1] "text/html; charset=UTF-8" [2] """ [3] " http-equiv=" [4] Object: [doubleQuote] [0] """ [1] "content-type" [2] """ [5] ">" [10] "\n" [11] Object: [kakko<>] [0] "<" [1] "script" [2] ">" [12] Object: [javascript] [0] "\nconsole.clear" [1] Object: [kakko()] [0] "(" [1] ")" [2] ";" [3] "\naddEventListener" [4] Object: [kakko()] [0] "(" [1] " " [2] Object: [doubleQuote] [0] """ [1] "load" [2] """ [3] ", " [4] Object: [functionExpression] [0] "function" [1] Object: [kakko()] [0] "(" [1] " e " [2] ")" [2] " " [3] Object: [kakko{}] [0] "{" [1] "\n\tlet div = document.createElement" [2] Object: [kakko()] [0] "(" [1] " " [2] Object: [doubleQuote] [0] """ [1] "div" [2] """ [3] " " [4] ")" [3] ";" [4] "\n\t\tObject.assign" [5] Object: [kakko()] [0] "(" [1] " div.style, " [2] Object: [kakko{}] [0] "{" [1] "\n\t\t\tposition : " [2] Object: [doubleQuote] [0] """ [1] "fixed" [2] """ [3] ",\n\t\t\ttop : 0,\n\t\t\tright : 0,\n\t\t\tfontSize : " [4] Object: [doubleQuote] [0] """ [1] "small" [2] """ [5] ",\n\t\t\tpadding : " [6] Object: [doubleQuote] [0] """ [1] ".5em" [2] """ [7] ",\n\t\t\tcolor : " [8] Object: [doubleQuote] [0] """ [1] "gray" [2] """ [9] ",\n\t\t" [10] "}" [3] " " [4] ")" [6] ";" [7] "\n\t\tdiv.innerHTML = decodeURI" [8] Object: [kakko()] [0] "(" [1] " location.href.match" [2] Object: [kakko()] [0] "(" [1] " " [2] Object: [regExp] [0] "/" [1] "[^\/]+\/[^\/]+$" [2] "/" [3] " " [4] ")" [3] " " [4] ")" [9] ";" [10] "\n\tdocument.body.appendChild" [11] Object: [kakko()] [0] "(" [1] " div " [2] ")" [12] ";" [13] "\n" [14] "}" [5] " " [6] ")" [5] ";" [6] "\n\n\n" [7] Object: [functionStatement] [0] "function createStatement" [1] Object: [kakko()] [0] "(" [1] " name, parent " [2] ")" [2] " " [3] Object: [kakko{}] [0] "{" [1] "\n\tlet statement = " [2] Object: [kakko{}] [0] "{" [1] "\n\t\tname : name,\n\t\tparent : parent,\n\t\tchildren : new Array" [2] Object: [kakko()] [0] "(" [1] ")" [3] ",\n\t" [4] "}" [3] "\n\treturn statement" [4] ";" [5] "\n" [6] "}" [8] "\n\n" [9] Object: [functionStatement] [0] "function allEscape" [1] Object: [kakko()] [0] "(" [1] " string " [2] ")" [2] " " [3] Object: [kakko{}] [0] "{" [1] "\n\t\t" [2] Object: [lineComment] [0] "//" [1] "check." [2] "\n" [3] "\t\t" [4] Object: [ifStatement] [0] "if" [1] Object: [kakko()] [0] "(" [1] " typeof string === " [2] Object: [doubleQuote] [0] """ [1] "undefined" [2] """ [3] " " [4] ")" [2] " return" [3] ";" [5] "\n\t\t\n\tlet res = " [6] Object: [doubleQuote] [0] """ [1] """ [7] ";" [8] "\n\t" [9] Object: [forStatement] [0] "for" [1] Object: [kakko()] [0] "(" [1] " let ch of string " [2] ")" [2] " " [3] Object: [kakko{}] [0] "{" [1] "\n\t\t" [2] Object: [ifStatement] [0] "if" [1] Object: [kakko()] [0] "(" [1] " " [2] Object: [doubleQuote] [0] """ [1] "[](){}/*.+|^$\\" [2] """ [3] ".indexOf" [4] Object: [kakko()] [0] "(" [1] " ch " [2] ")" [5] " > -1 " [6] ")" [2] "\n\t\t\tres += " [3] Object: [doubleQuote] [0] """ [1] "\\" [2] """ [4] " + ch" [5] ";" [6] "\n\t\t" [7] Object: [elseStatement] [0] "else" [1] "\n\t\t\tres += ch" [2] ";" [3] "\n\t" [4] "}" [10] "\n\treturn res" [11] ";" [12] "\n" [13] "}" [10] "\n\n\n" [11] Object: [functionStatement] [0] "function AL" [1] Object: [kakko()] [0] "(" [1] " array " [2] ")" [2] " " [3] Object: [kakko{}] [0] "{" [1] "\n\treturn array" [2] Object: [kakko[]] [0] "[" [1] " array.length - 1 " [2] "]" [3] ";" [4] "\n" [5] "}" [12] "\n\n" [13] Object: [functionStatement] [0] "function LOMToText" [1] Object: [kakko()] [0] "(" [1] " LOM " [2] ")" [2] " " [3] Object: [kakko{}] [0] "{" [1] "\n\tlet text = " [2] Object: [doubleQuote] [0] """ [1] """ [3] ";" [4] "\n\t" [5] Object: [forStatement] [0] "for" [1] Object: [kakko()] [0] "(" [1] " let child of LOM.children " [2] ")" [2] " " [3] Object: [kakko{}] [0] "{" [1] "\n\t\t" [2] Object: [ifStatement] [0] "if" [1] Object: [kakko()] [0] "(" [1] " typeof child === " [2] Object: [doubleQuote] [0] """ [1] "string" [2] """ [3] " " [4] ")" [2] " " [3] Object: [kakko{}] [0] "{" [1] "\n\t\t\ttext += child" [2] ";" [3] "\n\t\t" [4] "}" [4] " " [5] Object: [elseStatement] [0] "else" [1] " " [2] Object: [kakko{}] [0] "{" [1] "\n\t\t\ttext += LOMToText" [2] Object: [kakko()] [0] "(" [1] " child " [2] ")" [3] ";" [4] "\n\t\t" [5] "}" [3] "\n\t" [4] "}" [6] "\n\treturn text" [7] ";" [8] "\n" [9] "}" [14] "\n\n\n" [15] Object: [lineComment] [0] "//" [1] "===●●● main." [2] "\n" [16] Object: [functionStatement] [0] "function run" [1] Object: [kakko()] [0] "(" [1] ")" [2] " " [3] Object: [kakko{}] [0] "{" [1] "\n\n\tlet ta0 = document.getElementById" [2] Object: [kakko()] [0] "(" [1] " " [2] Object: [doubleQuote] [0] """ [1] "ta0" [2] """ [3] " " [4] ")" [3] ";" [4] "\n\t\tta0.style.backgroundColor = " [5] Object: [doubleQuote] [0] """ [1] "navy" [2] """ [6] ";" [7] "\n\t\tta0.style.color = " [8] Object: [doubleQuote] [0] """ [1] "white" [2] """ [9] ";" [10] "\n\n\tLOM = textToLOM" [11] Object: [kakko()] [0] "(" [1] " text0.value, ta0.value " [2] ")" [12] ";" [13] "\n\n\tconsole.log" [14] Object: [kakko()] [0] "(" [1] " " [2] Object: [doubleQuote] [0] """ [1] "//=== ここから　debug1" [2] """ [3] " " [4] ")" [15] ";" [16] "\n\ttaLog.value = " [17] Object: [doubleQuote] [0] """ [1] """ [18] ";" [19] "\n\tlog = " [20] Object: [functionExpression] [0] "function" [1] Object: [kakko()] [0] "(" [1] ")" [2] " " [3] Object: [kakko{}] [0] "{" [1] "\n\t\tlet array = Array.from" [2] Object: [kakko()] [0] "(" [1] " arguments " [2] ")" [3] ";" [4] "\n\t\ttaLog.value += array.join" [5] Object: [kakko()] [0] "(" [1] " " [2] Object: [doubleQuote] [0] """ [1] " " [2] """ [3] " " [4] ")" [6] ".replace" [7] Object: [kakko()] [0] "(" [1] " " [2] Object: [regExp] [0] "/" [1] "^ +" [2] "/" [3] ", " [4] Object: [doubleQuote] [0] """ [1] """ [5] " " [6] ")" [8] ";" [9] "\n\t\ttaLog.value += " [10] Object: [doubleQuote] [0] """ [1] "\n" [2] """ [11] ";" [12] "\n\t" [13] "}"
（中略）
[23] "\n" [13] Object: [kakko<>] [0] "<" [1] "/script" [2] ">" [14] "\n" [15] Object: [kakko<>] [0] "<" [1] "style" [2] ">" [16] "\n" [17] Object: [kakko<>] [0] "<" [1] "/style" [2] ">" [18] "\n" [19] Object: [kakko<>] [0] "<" [1] "/head" [2] ">" [20] "\n" [21] Object: [kakko<>] [0] "<" [1] "body onload=" [2] Object: [doubleQuote] [0] """ [1] "run()" [2] """ [3] ">" [22] "\nHello World!" [23] Object: [kakko<>] [0] "<" [1] "span id=" [2] Object: [doubleQuote] [0] """ [1] "gage" [2] """ [3] ">" [24] Object: [kakko<>] [0] "<" [1] "/span" [2] ">" [25] "\n" [26] Object: [kakko<>] [0] "<" [1] "BR" [2] ">" [27] "\n" [28] Object: [kakko<>] [0] "<" [1] "input type=" [2] Object: [doubleQuote] [0] """ [1] "text" [2] """ [3] " id=" [4] Object: [doubleQuote] [0] """ [1] "text0" [2] """ [5] ">" [29] Object: [kakko<>] [0] "<" [1] "BR" [2] ">" [30] "\n" [31] Object: [kakko<>] [0] "<" [1] "textarea id=" [2] Object: [doubleQuote] [0] """ [1] "ta0" [2] """ [3] " cmt=" [4] Object: [doubleQuote] [0] """ [1] "disabled autocomplete=off" [2] """ [5] " style=" [6] Object: [doubleQuote] [0] """ [1] "\n\twidth : 100%;\n\theight : 45vh;\n" [2] """ [7] ">" [32] Object: [taggedByTextarea] [33] Object: [kakko<>] [0] "<" [1] "/textarea" [2] ">" [34] "\n" [35] Object: [kakko<>] [0] "<" [1] "textarea id=" [2] Object: [doubleQuote] [0] """ [1] "taLog" [2] """ [3] " cmt=" [4] Object: [doubleQuote] [0] """ [1] "disabled autocomplete=off" [2] """ [5] " style=" [6] Object: [doubleQuote] [0] """ [1] "\n\twidth : 100%;\n\theight : 45vh;\n" [2] """ [7] ">" [36] Object: [taggedByTextarea] [37] Object: [kakko<>] [0] "<" [1] "/textarea" [2] ">" [38] "\n\n\n" [39] Object: [kakko<>] [0] "<" [1] "/body" [2] ">" [40] "\n" [41] Object: [kakko<>] [0] "<" [1] "/html" [2] ">" [42] "\n"

ちゃんと正しく認識されています。

ところで、文字列認識の「正規表現」は /abc/i と書くことで文字列内に abc や ABC が存在している、その存在の手前の文字列や後の文字列なども参照できるという便利な機能です。

構文解析においては、正規表現の開始と終了を示す / という記号を「割り算」と混同しないように工夫をしなければなりません。

そういう「正しく認識」させるための工夫を最小限に抑えることが必要です。

あまり長くて複雑なプログラムを作っても、バグ修正は大変だし、あとからの機能拡張も大変になってしまうので、最小限を目指したほうがよいです。

この構文解析を行えると何が楽しいのかというと、

• プログラムを作った後、構文解析を利用してフローチャートを自動的に作成できる。
• RPG などのゲームプログラム内で使われる「簡易的なスクリプト言語」を、ブロック構造や if や for などの入れ子を正しく認識しつつ実行できる。
• プログラミング言語を自分で作成できる。

2025年3月2日

2体セットで、１２８０円税込でした。

箱から出して、そのまま何もいじらないで立たせたら、普通に「ジョジョ立ち」でした。

ゴゴゴゴゴ

なにィー！コイツ!!最初からジョジョ立ち！

荒木飛呂彦の世界。

今後、私に画家の魂が少しでも入ってくれることを期待します。

もっとリアルな可動範囲抜群のデッサン人形も売られていますが、昔ながらの方が魂が入るかなと思って。