private scanTemplate()

in src/scanner.ts [964:1088]
116 lines of code
28 McCabe index (conditional complexity)

    private scanTemplate(): RawToken {
        let cooked = '';
        let terminated = false;
        const start = this.index;

        const head = (this.source[start] === '`');
        let tail = false;
        let rawOffset = 2;

        ++this.index;

        while (!this.eof()) {
            let ch = this.source[this.index++];
            if (ch === '`') {
                rawOffset = 1;
                tail = true;
                terminated = true;
                break;
            } else if (ch === '$') {
                if (this.source[this.index] === '{') {
                    this.curlyStack.push('${');
                    ++this.index;
                    terminated = true;
                    break;
                }
                cooked += ch;
            } else if (ch === '\\') {
                ch = this.source[this.index++];
                if (!Character.isLineTerminator(ch.charCodeAt(0))) {
                    switch (ch) {
                        case 'n':
                            cooked += '\n';
                            break;
                        case 'r':
                            cooked += '\r';
                            break;
                        case 't':
                            cooked += '\t';
                            break;
                        case 'u':
                            if (this.source[this.index] === '{') {
                                ++this.index;
                                cooked += this.scanUnicodeCodePointEscape();
                            } else {
                                const restore = this.index;
                                const unescapedChar = this.scanHexEscape(ch);
                                if (unescapedChar !== null) {
                                    cooked += unescapedChar;
                                } else {
                                    this.index = restore;
                                    cooked += ch;
                                }
                            }
                            break;
                        case 'x':
                            const unescaped = this.scanHexEscape(ch);
                            if (unescaped === null) {
                                this.throwUnexpectedToken(Messages.InvalidHexEscapeSequence);
                            }
                            cooked += unescaped;
                            break;
                        case 'b':
                            cooked += '\b';
                            break;
                        case 'f':
                            cooked += '\f';
                            break;
                        case 'v':
                            cooked += '\v';
                            break;

                        default:
                            if (ch === '0') {
                                if (Character.isDecimalDigit(this.source.charCodeAt(this.index))) {
                                    // Illegal: \01 \02 and so on
                                    this.throwUnexpectedToken(Messages.TemplateOctalLiteral);
                                }
                                cooked += '\0';
                            } else if (Character.isOctalDigit(ch.charCodeAt(0))) {
                                // Illegal: \1 \2
                                this.throwUnexpectedToken(Messages.TemplateOctalLiteral);
                            } else {
                                cooked += ch;
                            }
                            break;
                    }
                } else {
                    ++this.lineNumber;
                    if (ch === '\r' && this.source[this.index] === '\n') {
                        ++this.index;
                    }
                    this.lineStart = this.index;
                }
            } else if (Character.isLineTerminator(ch.charCodeAt(0))) {
                ++this.lineNumber;
                if (ch === '\r' && this.source[this.index] === '\n') {
                    ++this.index;
                }
                this.lineStart = this.index;
                cooked += '\n';
            } else {
                cooked += ch;
            }
        }

        if (!terminated) {
            this.throwUnexpectedToken();
        }

        if (!head) {
            this.curlyStack.pop();
        }

        return {
            type: Token.Template,
            value: this.source.slice(start + 1, this.index - rawOffset),
            cooked: cooked,
            head: head,
            tail: tail,
            lineNumber: this.lineNumber,
            lineStart: this.lineStart,
            start: start,
            end: this.index
        };
    }