First commit.

Signed-off-by: Chen Xiao <abigwc@gmail.com>

client/node_modules/@chevrotain/regexp-to-ast/lib/src/regexp-parser.js

@@ -0,0 +1,744 @@
+import { addFlag, ASSERT_EXISTS, ASSERT_NEVER_REACH_HERE, cc, insertToSet, isCharacter, } from "./utils.js";
+import { digitsCharCodes, whitespaceCodes, wordCharCodes, } from "./character-classes.js";
+// consts and utilities
+const hexDigitPattern = /[0-9a-fA-F]/;
+const decimalPattern = /[0-9]/;
+const decimalPatternNoZero = /[1-9]/;
+// https://hackernoon.com/the-madness-of-parsing-real-world-javascript-regexps-d9ee336df983
+// https://www.ecma-international.org/ecma-262/8.0/index.html#prod-Pattern
+export class RegExpParser {
+    constructor() {
+        this.idx = 0;
+        this.input = "";
+        this.groupIdx = 0;
+    }
+    saveState() {
+        return {
+            idx: this.idx,
+            input: this.input,
+            groupIdx: this.groupIdx,
+        };
+    }
+    restoreState(newState) {
+        this.idx = newState.idx;
+        this.input = newState.input;
+        this.groupIdx = newState.groupIdx;
+    }
+    pattern(input) {
+        // parser state
+        this.idx = 0;
+        this.input = input;
+        this.groupIdx = 0;
+        this.consumeChar("/");
+        const value = this.disjunction();
+        this.consumeChar("/");
+        const flags = {
+            type: "Flags",
+            loc: { begin: this.idx, end: input.length },
+            global: false,
+            ignoreCase: false,
+            multiLine: false,
+            unicode: false,
+            sticky: false,
+        };
+        while (this.isRegExpFlag()) {
+            switch (this.popChar()) {
+                case "g":
+                    addFlag(flags, "global");
+                    break;
+                case "i":
+                    addFlag(flags, "ignoreCase");
+                    break;
+                case "m":
+                    addFlag(flags, "multiLine");
+                    break;
+                case "u":
+                    addFlag(flags, "unicode");
+                    break;
+                case "y":
+                    addFlag(flags, "sticky");
+                    break;
+            }
+        }
+        if (this.idx !== this.input.length) {
+            throw Error("Redundant input: " + this.input.substring(this.idx));
+        }
+        return {
+            type: "Pattern",
+            flags: flags,
+            value: value,
+            loc: this.loc(0),
+        };
+    }
+    disjunction() {
+        const alts = [];
+        const begin = this.idx;
+        alts.push(this.alternative());
+        while (this.peekChar() === "|") {
+            this.consumeChar("|");
+            alts.push(this.alternative());
+        }
+        return { type: "Disjunction", value: alts, loc: this.loc(begin) };
+    }
+    alternative() {
+        const terms = [];
+        const begin = this.idx;
+        while (this.isTerm()) {
+            terms.push(this.term());
+        }
+        return { type: "Alternative", value: terms, loc: this.loc(begin) };
+    }
+    term() {
+        if (this.isAssertion()) {
+            return this.assertion();
+        }
+        else {
+            return this.atom();
+        }
+    }
+    assertion() {
+        const begin = this.idx;
+        switch (this.popChar()) {
+            case "^":
+                return {
+                    type: "StartAnchor",
+                    loc: this.loc(begin),
+                };
+            case "$":
+                return { type: "EndAnchor", loc: this.loc(begin) };
+            // '\b' or '\B'
+            case "\\":
+                switch (this.popChar()) {
+                    case "b":
+                        return {
+                            type: "WordBoundary",
+                            loc: this.loc(begin),
+                        };
+                    case "B":
+                        return {
+                            type: "NonWordBoundary",
+                            loc: this.loc(begin),
+                        };
+                }
+                /* c8 ignore next */
+                throw Error("Invalid Assertion Escape");
+            // '(?=' or '(?!'
+            case "(":
+                this.consumeChar("?");
+                let type;
+                switch (this.popChar()) {
+                    case "=":
+                        type = "Lookahead";
+                        break;
+                    case "!":
+                        type = "NegativeLookahead";
+                        break;
+                    case "<": {
+                        switch (this.popChar()) {
+                            case "=":
+                                type = "Lookbehind";
+                                break;
+                            case "!":
+                                type = "NegativeLookbehind";
+                        }
+                        break;
+                    }
+                }
+                ASSERT_EXISTS(type);
+                const disjunction = this.disjunction();
+                this.consumeChar(")");
+                return {
+                    type: type,
+                    value: disjunction,
+                    loc: this.loc(begin),
+                };
+        }
+        // istanbul ignore next
+        return ASSERT_NEVER_REACH_HERE();
+    }
+    quantifier(isBacktracking = false) {
+        let range = undefined;
+        const begin = this.idx;
+        switch (this.popChar()) {
+            case "*":
+                range = {
+                    atLeast: 0,
+                    atMost: Infinity,
+                };
+                break;
+            case "+":
+                range = {
+                    atLeast: 1,
+                    atMost: Infinity,
+                };
+                break;
+            case "?":
+                range = {
+                    atLeast: 0,
+                    atMost: 1,
+                };
+                break;
+            case "{":
+                const atLeast = this.integerIncludingZero();
+                switch (this.popChar()) {
+                    case "}":
+                        range = {
+                            atLeast: atLeast,
+                            atMost: atLeast,
+                        };
+                        break;
+                    case ",":
+                        let atMost;
+                        if (this.isDigit()) {
+                            atMost = this.integerIncludingZero();
+                            range = {
+                                atLeast: atLeast,
+                                atMost: atMost,
+                            };
+                        }
+                        else {
+                            range = {
+                                atLeast: atLeast,
+                                atMost: Infinity,
+                            };
+                        }
+                        this.consumeChar("}");
+                        break;
+                }
+                // throwing exceptions from "ASSERT_EXISTS" during backtracking
+                // causes severe performance degradations
+                if (isBacktracking === true && range === undefined) {
+                    return undefined;
+                }
+                ASSERT_EXISTS(range);
+                break;
+        }
+        // throwing exceptions from "ASSERT_EXISTS" during backtracking
+        // causes severe performance degradations
+        if (isBacktracking === true && range === undefined) {
+            return undefined;
+        }
+        // istanbul ignore else
+        if (ASSERT_EXISTS(range)) {
+            if (this.peekChar(0) === "?") {
+                this.consumeChar("?");
+                range.greedy = false;
+            }
+            else {
+                range.greedy = true;
+            }
+            range.type = "Quantifier";
+            range.loc = this.loc(begin);
+            return range;
+        }
+    }
+    atom() {
+        let atom;
+        const begin = this.idx;
+        switch (this.peekChar()) {
+            case ".":
+                atom = this.dotAll();
+                break;
+            case "\\":
+                atom = this.atomEscape();
+                break;
+            case "[":
+                atom = this.characterClass();
+                break;
+            case "(":
+                atom = this.group();
+                break;
+        }
+        if (atom === undefined && this.isPatternCharacter()) {
+            atom = this.patternCharacter();
+        }
+        // istanbul ignore else
+        if (ASSERT_EXISTS(atom)) {
+            atom.loc = this.loc(begin);
+            if (this.isQuantifier()) {
+                atom.quantifier = this.quantifier();
+            }
+            return atom;
+        }
+        // istanbul ignore next
+        return ASSERT_NEVER_REACH_HERE();
+    }
+    dotAll() {
+        this.consumeChar(".");
+        return {
+            type: "Set",
+            complement: true,
+            value: [cc("\n"), cc("\r"), cc("\u2028"), cc("\u2029")],
+        };
+    }
+    atomEscape() {
+        this.consumeChar("\\");
+        switch (this.peekChar()) {
+            case "1":
+            case "2":
+            case "3":
+            case "4":
+            case "5":
+            case "6":
+            case "7":
+            case "8":
+            case "9":
+                return this.decimalEscapeAtom();
+            case "d":
+            case "D":
+            case "s":
+            case "S":
+            case "w":
+            case "W":
+                return this.characterClassEscape();
+            case "f":
+            case "n":
+            case "r":
+            case "t":
+            case "v":
+                return this.controlEscapeAtom();
+            case "c":
+                return this.controlLetterEscapeAtom();
+            case "0":
+                return this.nulCharacterAtom();
+            case "x":
+                return this.hexEscapeSequenceAtom();
+            case "u":
+                return this.regExpUnicodeEscapeSequenceAtom();
+            default:
+                return this.identityEscapeAtom();
+        }
+    }
+    decimalEscapeAtom() {
+        const value = this.positiveInteger();
+        return { type: "GroupBackReference", value: value };
+    }
+    characterClassEscape() {
+        let set;
+        let complement = false;
+        switch (this.popChar()) {
+            case "d":
+                set = digitsCharCodes;
+                break;
+            case "D":
+                set = digitsCharCodes;
+                complement = true;
+                break;
+            case "s":
+                set = whitespaceCodes;
+                break;
+            case "S":
+                set = whitespaceCodes;
+                complement = true;
+                break;
+            case "w":
+                set = wordCharCodes;
+                break;
+            case "W":
+                set = wordCharCodes;
+                complement = true;
+                break;
+        }
+        // istanbul ignore else
+        if (ASSERT_EXISTS(set)) {
+            return { type: "Set", value: set, complement: complement };
+        }
+        // istanbul ignore next
+        return ASSERT_NEVER_REACH_HERE();
+    }
+    controlEscapeAtom() {
+        let escapeCode;
+        switch (this.popChar()) {
+            case "f":
+                escapeCode = cc("\f");
+                break;
+            case "n":
+                escapeCode = cc("\n");
+                break;
+            case "r":
+                escapeCode = cc("\r");
+                break;
+            case "t":
+                escapeCode = cc("\t");
+                break;
+            case "v":
+                escapeCode = cc("\v");
+                break;
+        }
+        // istanbul ignore else
+        if (ASSERT_EXISTS(escapeCode)) {
+            return { type: "Character", value: escapeCode };
+        }
+        // istanbul ignore next
+        return ASSERT_NEVER_REACH_HERE();
+    }
+    controlLetterEscapeAtom() {
+        this.consumeChar("c");
+        const letter = this.popChar();
+        if (/[a-zA-Z]/.test(letter) === false) {
+            throw Error("Invalid ");
+        }
+        const letterCode = letter.toUpperCase().charCodeAt(0) - 64;
+        return { type: "Character", value: letterCode };
+    }
+    nulCharacterAtom() {
+        // TODO implement '[lookahead ∉ DecimalDigit]'
+        // TODO: for the deprecated octal escape sequence
+        this.consumeChar("0");
+        return { type: "Character", value: cc("\0") };
+    }
+    hexEscapeSequenceAtom() {
+        this.consumeChar("x");
+        return this.parseHexDigits(2);
+    }
+    regExpUnicodeEscapeSequenceAtom() {
+        this.consumeChar("u");
+        return this.parseHexDigits(4);
+    }
+    identityEscapeAtom() {
+        // TODO: implement "SourceCharacter but not UnicodeIDContinue"
+        // // http://unicode.org/reports/tr31/#Specific_Character_Adjustments
+        const escapedChar = this.popChar();
+        return { type: "Character", value: cc(escapedChar) };
+    }
+    classPatternCharacterAtom() {
+        switch (this.peekChar()) {
+            // istanbul ignore next
+            case "\n":
+            // istanbul ignore next
+            case "\r":
+            // istanbul ignore next
+            case "\u2028":
+            // istanbul ignore next
+            case "\u2029":
+            // istanbul ignore next
+            case "\\":
+            // istanbul ignore next
+            case "]":
+                throw Error("TBD");
+            default:
+                const nextChar = this.popChar();
+                return { type: "Character", value: cc(nextChar) };
+        }
+    }
+    characterClass() {
+        const set = [];
+        let complement = false;
+        this.consumeChar("[");
+        if (this.peekChar(0) === "^") {
+            this.consumeChar("^");
+            complement = true;
+        }
+        while (this.isClassAtom()) {
+            const from = this.classAtom();
+            const isFromSingleChar = from.type === "Character";
+            if (isCharacter(from) && this.isRangeDash()) {
+                this.consumeChar("-");
+                const to = this.classAtom();
+                const isToSingleChar = to.type === "Character";
+                // a range can only be used when both sides are single characters
+                if (isCharacter(to)) {
+                    if (to.value < from.value) {
+                        throw Error("Range out of order in character class");
+                    }
+                    set.push({ from: from.value, to: to.value });
+                }
+                else {
+                    // literal dash
+                    insertToSet(from.value, set);
+                    set.push(cc("-"));
+                    insertToSet(to.value, set);
+                }
+            }
+            else {
+                insertToSet(from.value, set);
+            }
+        }
+        this.consumeChar("]");
+        return { type: "Set", complement: complement, value: set };
+    }
+    classAtom() {
+        switch (this.peekChar()) {
+            // istanbul ignore next
+            case "]":
+            // istanbul ignore next
+            case "\n":
+            // istanbul ignore next
+            case "\r":
+            // istanbul ignore next
+            case "\u2028":
+            // istanbul ignore next
+            case "\u2029":
+                throw Error("TBD");
+            case "\\":
+                return this.classEscape();
+            default:
+                return this.classPatternCharacterAtom();
+        }
+    }
+    classEscape() {
+        this.consumeChar("\\");
+        switch (this.peekChar()) {
+            // Matches a backspace.
+            // (Not to be confused with \b word boundary outside characterClass)
+            case "b":
+                this.consumeChar("b");
+                return { type: "Character", value: cc("\u0008") };
+            case "d":
+            case "D":
+            case "s":
+            case "S":
+            case "w":
+            case "W":
+                return this.characterClassEscape();
+            case "f":
+            case "n":
+            case "r":
+            case "t":
+            case "v":
+                return this.controlEscapeAtom();
+            case "c":
+                return this.controlLetterEscapeAtom();
+            case "0":
+                return this.nulCharacterAtom();
+            case "x":
+                return this.hexEscapeSequenceAtom();
+            case "u":
+                return this.regExpUnicodeEscapeSequenceAtom();
+            default:
+                return this.identityEscapeAtom();
+        }
+    }
+    group() {
+        let capturing = true;
+        this.consumeChar("(");
+        switch (this.peekChar(0)) {
+            case "?":
+                this.consumeChar("?");
+                this.consumeChar(":");
+                capturing = false;
+                break;
+            default:
+                this.groupIdx++;
+                break;
+        }
+        const value = this.disjunction();
+        this.consumeChar(")");
+        const groupAst = {
+            type: "Group",
+            capturing: capturing,
+            value: value,
+        };
+        if (capturing) {
+            groupAst["idx"] = this.groupIdx;
+        }
+        return groupAst;
+    }
+    positiveInteger() {
+        let number = this.popChar();
+        // istanbul ignore next - can't ever get here due to previous lookahead checks
+        // still implementing this error checking in case this ever changes.
+        if (decimalPatternNoZero.test(number) === false) {
+            throw Error("Expecting a positive integer");
+        }
+        while (decimalPattern.test(this.peekChar(0))) {
+            number += this.popChar();
+        }
+        return parseInt(number, 10);
+    }
+    integerIncludingZero() {
+        let number = this.popChar();
+        if (decimalPattern.test(number) === false) {
+            throw Error("Expecting an integer");
+        }
+        while (decimalPattern.test(this.peekChar(0))) {
+            number += this.popChar();
+        }
+        return parseInt(number, 10);
+    }
+    patternCharacter() {
+        const nextChar = this.popChar();
+        switch (nextChar) {
+            // istanbul ignore next
+            case "\n":
+            // istanbul ignore next
+            case "\r":
+            // istanbul ignore next
+            case "\u2028":
+            // istanbul ignore next
+            case "\u2029":
+            // istanbul ignore next
+            case "^":
+            // istanbul ignore next
+            case "$":
+            // istanbul ignore next
+            case "\\":
+            // istanbul ignore next
+            case ".":
+            // istanbul ignore next
+            case "*":
+            // istanbul ignore next
+            case "+":
+            // istanbul ignore next
+            case "?":
+            // istanbul ignore next
+            case "(":
+            // istanbul ignore next
+            case ")":
+            // istanbul ignore next
+            case "[":
+            // istanbul ignore next
+            case "|":
+                // istanbul ignore next
+                throw Error("TBD");
+            default:
+                return { type: "Character", value: cc(nextChar) };
+        }
+    }
+    isRegExpFlag() {
+        switch (this.peekChar(0)) {
+            case "g":
+            case "i":
+            case "m":
+            case "u":
+            case "y":
+                return true;
+            default:
+                return false;
+        }
+    }
+    isRangeDash() {
+        return this.peekChar() === "-" && this.isClassAtom(1);
+    }
+    isDigit() {
+        return decimalPattern.test(this.peekChar(0));
+    }
+    isClassAtom(howMuch = 0) {
+        switch (this.peekChar(howMuch)) {
+            case "]":
+            case "\n":
+            case "\r":
+            case "\u2028":
+            case "\u2029":
+                return false;
+            default:
+                return true;
+        }
+    }
+    isTerm() {
+        return this.isAtom() || this.isAssertion();
+    }
+    isAtom() {
+        if (this.isPatternCharacter()) {
+            return true;
+        }
+        switch (this.peekChar(0)) {
+            case ".":
+            case "\\": // atomEscape
+            case "[": // characterClass
+            // TODO: isAtom must be called before isAssertion - disambiguate
+            case "(": // group
+                return true;
+            default:
+                return false;
+        }
+    }
+    isAssertion() {
+        switch (this.peekChar(0)) {
+            case "^":
+            case "$":
+                return true;
+            // '\b' or '\B'
+            case "\\":
+                switch (this.peekChar(1)) {
+                    case "b":
+                    case "B":
+                        return true;
+                    default:
+                        return false;
+                }
+            // '(?=' or '(?!' or `(?<=` or `(?<!`
+            case "(":
+                return (this.peekChar(1) === "?" &&
+                    (this.peekChar(2) === "=" ||
+                        this.peekChar(2) === "!" ||
+                        (this.peekChar(2) === "<" &&
+                            (this.peekChar(3) === "=" || this.peekChar(3) === "!"))));
+            default:
+                return false;
+        }
+    }
+    isQuantifier() {
+        const prevState = this.saveState();
+        try {
+            return this.quantifier(true) !== undefined;
+        }
+        catch (e) {
+            return false;
+        }
+        finally {
+            this.restoreState(prevState);
+        }
+    }
+    isPatternCharacter() {
+        switch (this.peekChar()) {
+            case "^":
+            case "$":
+            case "\\":
+            case ".":
+            case "*":
+            case "+":
+            case "?":
+            case "(":
+            case ")":
+            case "[":
+            case "|":
+            case "/":
+            case "\n":
+            case "\r":
+            case "\u2028":
+            case "\u2029":
+                return false;
+            default:
+                return true;
+        }
+    }
+    parseHexDigits(howMany) {
+        let hexString = "";
+        for (let i = 0; i < howMany; i++) {
+            const hexChar = this.popChar();
+            if (hexDigitPattern.test(hexChar) === false) {
+                throw Error("Expecting a HexDecimal digits");
+            }
+            hexString += hexChar;
+        }
+        const charCode = parseInt(hexString, 16);
+        return { type: "Character", value: charCode };
+    }
+    peekChar(howMuch = 0) {
+        return this.input[this.idx + howMuch];
+    }
+    popChar() {
+        const nextChar = this.peekChar(0);
+        this.consumeChar(undefined);
+        return nextChar;
+    }
+    consumeChar(char) {
+        if (char !== undefined && this.input[this.idx] !== char) {
+            throw Error("Expected: '" +
+                char +
+                "' but found: '" +
+                this.input[this.idx] +
+                "' at offset: " +
+                this.idx);
+        }
+        if (this.idx >= this.input.length) {
+            throw Error("Unexpected end of input");
+        }
+        this.idx++;
+    }
+    loc(begin) {
+        return { begin: begin, end: this.idx };
+    }
+}
+//# sourceMappingURL=regexp-parser.js.map