private scanNumericLiteral()

in src/scanner.ts [777:854]
65 lines of code
23 McCabe index (conditional complexity)

    private scanNumericLiteral(): RawToken {
        const start = this.index;
        let ch = this.source[start];
        assert(Character.isDecimalDigit(ch.charCodeAt(0)) || (ch === '.'),
            'Numeric literal must start with a decimal digit or a decimal point');

        let num = '';
        if (ch !== '.') {
            num = this.source[this.index++];
            ch = this.source[this.index];

            // Hex number starts with '0x'.
            // Octal number starts with '0'.
            // Octal number in ES6 starts with '0o'.
            // Binary number in ES6 starts with '0b'.
            if (num === '0') {
                if (ch === 'x' || ch === 'X') {
                    ++this.index;
                    return this.scanHexLiteral(start);
                }
                if (ch === 'b' || ch === 'B') {
                    ++this.index;
                    return this.scanBinaryLiteral(start);
                }
                if (ch === 'o' || ch === 'O') {
                    return this.scanOctalLiteral(ch, start);
                }

                if (ch && Character.isOctalDigit(ch.charCodeAt(0))) {
                    if (this.isImplicitOctalLiteral()) {
                        return this.scanOctalLiteral(ch, start);
                    }
                }
            }

            while (Character.isDecimalDigit(this.source.charCodeAt(this.index))) {
                num += this.source[this.index++];
            }
            ch = this.source[this.index];
        }

        if (ch === '.') {
            num += this.source[this.index++];
            while (Character.isDecimalDigit(this.source.charCodeAt(this.index))) {
                num += this.source[this.index++];
            }
            ch = this.source[this.index];
        }

        if (ch === 'e' || ch === 'E') {
            num += this.source[this.index++];

            ch = this.source[this.index];
            if (ch === '+' || ch === '-') {
                num += this.source[this.index++];
            }
            if (Character.isDecimalDigit(this.source.charCodeAt(this.index))) {
                while (Character.isDecimalDigit(this.source.charCodeAt(this.index))) {
                    num += this.source[this.index++];
                }
            } else {
                this.throwUnexpectedToken();
            }
        }

        if (Character.isIdentifierStart(this.source.charCodeAt(this.index))) {
            this.throwUnexpectedToken();
        }

        return {
            type: Token.NumericLiteral,
            value: parseFloat(num),
            lineNumber: this.lineNumber,
            lineStart: this.lineStart,
            start: start,
            end: this.index
        };
    }