public lex()

in src/scanner.ts [1248:1303]
40 lines of code
17 McCabe index (conditional complexity)

    public lex(): RawToken {
        if (this.eof()) {
            return {
                type: Token.EOF,
                value: '',
                lineNumber: this.lineNumber,
                lineStart: this.lineStart,
                start: this.index,
                end: this.index
            };
        }

        const cp = this.source.charCodeAt(this.index);

        if (Character.isIdentifierStart(cp)) {
            return this.scanIdentifier();
        }

        // Very common: ( and ) and ;
        if (cp === 0x28 || cp === 0x29 || cp === 0x3B) {
            return this.scanPunctuator();
        }

        // String literal starts with single quote (U+0027) or double quote (U+0022).
        if (cp === 0x27 || cp === 0x22) {
            return this.scanStringLiteral();
        }

        // Dot (.) U+002E can also start a floating-point number, hence the need
        // to check the next character.
        if (cp === 0x2E) {
            if (Character.isDecimalDigit(this.source.charCodeAt(this.index + 1))) {
                return this.scanNumericLiteral();
            }
            return this.scanPunctuator();
        }

        if (Character.isDecimalDigit(cp)) {
            return this.scanNumericLiteral();
        }

        // Template literals start with ` (U+0060) for template head
        // or } (U+007D) for template middle or template tail.
        if (cp === 0x60 || (cp === 0x7D && this.curlyStack[this.curlyStack.length - 1] === '${')) {
            return this.scanTemplate();
        }

        // Possible identifier start in a surrogate pair.
        if (cp >= 0xD800 && cp < 0xDFFF) {
            if (Character.isIdentifierStart(this.codePointAt(this.index))) {
                return this.scanIdentifier();
            }
        }

        return this.scanPunctuator();
    }