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js-tokens.mjs
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js-tokens.mjs
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// this is a vendored version of js-tokens by Simon Lydell,
// with the following modifications:
//
// - made it an ES6 module.
// - removed JSX-related code flow which is never used by Roadroller.
// - replaced long token names with exported numeric constants.
// - replaced pseudo-tokens like "?NonExpressionParenKeyword" with
// two-letter abbreviation like "?A" for the sake of size.
//
// Copyright 2014, 2015, 2016, 2017, 2018, 2019, 2020 Simon Lydell
// License: MIT.
const TAG_JS = 1;
const TAG_JSNonExpressionParen = 2;
const TAG_InterpolationInTemplate = 3;
export const TYPE_StringLiteral = 1;
export const TYPE_NoSubstitutionTemplate = 2;
export const TYPE_TemplateHead = 3;
export const TYPE_TemplateMiddle = 4;
export const TYPE_TemplateTail = 5;
export const TYPE_RegularExpressionLiteral = 6;
export const TYPE_MultiLineComment = 7;
export const TYPE_SingleLineComment = 8;
export const TYPE_IdentifierName = 9;
export const TYPE_NumericLiteral = 10;
export const TYPE_Punctuator = 11;
export const TYPE_WhiteSpace = 12;
export const TYPE_LineTerminatorSequence = 13;
export const TYPE_Invalid = 14;
const TOK_ExpressionBraceEnd = "?A";
const TOK_PostfixIncDec = "?B";
const TOK_UnaryIncDec = "?C";
const TOK_InterpolationInTemplate = "?D";
const TOK_NoLineTerminatorHere = "?E";
const TOK_NonExpressionParenEnd = "?F";
const TOK_NonExpressionParenKeyword = "?G";
const RegularExpressionLiteral = /\/(?![*\/])(?:\[(?:(?![\]\\]).|\\.)*\]|(?![\/\]\\]).|\\.)*(\/[$_\u200C\u200D\p{ID_Continue}]*|\\)?/yu;
const Punctuator = /--|\+\+|=>|\.{3}|\??\.(?!\d)|(?:&&|\|\||\?\?|[+\-%&|^]|\*{1,2}|<{1,2}|>{1,3}|!=?|={1,2}|\/(?![\/*]))=?|[?~,:;[\](){}]/y;
const IdentifierName = /(?=[$_\p{ID_Start}\\])(?:[$_\u200C\u200D\p{ID_Continue}]|\\u[\da-fA-F]{4}|\\u\{[\da-fA-F]+\})+/yu;
const StringLiteral = /(['"])(?:(?!\1)[^\\\n\r]|\\(?:\r\n|[^]))*(\1)?/y;
const NumericLiteral = /(?:0[xX][\da-fA-F](?:_?[\da-fA-F])*|0[oO][0-7](?:_?[0-7])*|0[bB][01](?:_?[01])*)n?|0n|[1-9](?:_?\d)*n|(?:(?:0(?!\d)|0\d*[89]\d*|[1-9](?:_?\d)*)(?:\.(?:\d(?:_?\d)*)?)?|\.\d(?:_?\d)*)(?:[eE][+-]?\d(?:_?\d)*)?|0[0-7]+/y;
const Template = /[`}](?:[^`\\$]|\\[^]|\$(?!\{))*(`|\$\{)?/y;
const WhiteSpace = /[\t\v\f\ufeff\p{Zs}]+/yu;
const LineTerminatorSequence = /\r?\n|[\r\u2028\u2029]/y;
const MultiLineComment = /\/\*(?:[^*]|\*(?!\/))*(\*\/)?/y;
const SingleLineComment = /\/\/.*/y;
// TOK_InterpolationInTemplate, TOK_NoLineTerminatorHere, TOK_NonExpressionParenEnd, TOK_UnaryIncDec
const TokensPrecedingExpression = /^(?:[\/+-]|\.{3}|\?[C-F])?$|[{}([,;<>=*%&|^!~?:]$/;
// TOK_NoLineTerminatorHere, TOK_NonExpressionParenEnd
const TokensNotPrecedingObjectLiteral = /^(?:=>|[;\]){}]|else|\?[EF])?$/;
const KeywordsWithExpressionAfter = /^(?:await|case|default|delete|do|else|instanceof|new|return|throw|typeof|void|yield)$/;
const KeywordsWithNoLineTerminatorAfter = /^(?:return|throw|yield)$/;
const Newline = RegExp(LineTerminatorSequence.source);
export function* jsTokens(input) {
var braces, firstCodePoint, isExpression, lastIndex, lastSignificantToken, length, match, mode, nextLastIndex, nextLastSignificantToken, parenNesting, postfixIncDec, punctuator, stack;
({length} = input);
lastIndex = 0;
lastSignificantToken = "";
stack = [
{tag: TAG_JS}
];
braces = [];
parenNesting = 0;
postfixIncDec = false;
while (lastIndex < length) {
mode = stack[stack.length - 1];
switch (mode.tag) {
case TAG_JS:
case TAG_JSNonExpressionParen:
case TAG_InterpolationInTemplate:
if (input[lastIndex] === "/" && (TokensPrecedingExpression.test(lastSignificantToken) || KeywordsWithExpressionAfter.test(lastSignificantToken))) {
RegularExpressionLiteral.lastIndex = lastIndex;
if (match = RegularExpressionLiteral.exec(input)) {
lastIndex = RegularExpressionLiteral.lastIndex;
lastSignificantToken = match[0];
postfixIncDec = true;
yield ({
type: TYPE_RegularExpressionLiteral,
value: match[0],
closed: match[1] !== void 0 && match[1] !== "\\"
});
continue;
}
}
Punctuator.lastIndex = lastIndex;
if (match = Punctuator.exec(input)) {
punctuator = match[0];
nextLastIndex = Punctuator.lastIndex;
nextLastSignificantToken = punctuator;
switch (punctuator) {
case "(":
if (lastSignificantToken === TOK_NonExpressionParenKeyword) {
stack.push({
tag: TAG_JSNonExpressionParen,
nesting: parenNesting
});
}
parenNesting++;
postfixIncDec = false;
break;
case ")":
parenNesting--;
postfixIncDec = true;
if (mode.tag === TAG_JSNonExpressionParen && parenNesting === mode.nesting) {
stack.pop();
nextLastSignificantToken = TOK_NonExpressionParenEnd;
postfixIncDec = false;
}
break;
case "{":
Punctuator.lastIndex = 0;
isExpression = !TokensNotPrecedingObjectLiteral.test(lastSignificantToken) && (TokensPrecedingExpression.test(lastSignificantToken) || KeywordsWithExpressionAfter.test(lastSignificantToken));
braces.push(isExpression);
postfixIncDec = false;
break;
case "}":
if (mode.tag === TAG_InterpolationInTemplate && braces.length === mode.nesting) {
Template.lastIndex = lastIndex;
match = Template.exec(input);
lastIndex = Template.lastIndex;
lastSignificantToken = match[0];
if (match[1] === "${") {
lastSignificantToken = TOK_InterpolationInTemplate;
postfixIncDec = false;
yield ({
type: TYPE_TemplateMiddle,
value: match[0]
});
} else {
stack.pop();
postfixIncDec = true;
yield ({
type: TYPE_TemplateTail,
value: match[0],
closed: match[1] === "`"
});
}
continue;
}
postfixIncDec = braces.pop();
nextLastSignificantToken = postfixIncDec ? TOK_ExpressionBraceEnd : "}";
break;
case "]":
postfixIncDec = true;
break;
case "++":
case "--":
nextLastSignificantToken = postfixIncDec ? TOK_PostfixIncDec : TOK_UnaryIncDec;
break;
case "<":
postfixIncDec = false;
break;
default:
postfixIncDec = false;
}
lastIndex = nextLastIndex;
lastSignificantToken = nextLastSignificantToken;
yield ({
type: TYPE_Punctuator,
value: punctuator
});
continue;
}
IdentifierName.lastIndex = lastIndex;
if (match = IdentifierName.exec(input)) {
lastIndex = IdentifierName.lastIndex;
nextLastSignificantToken = match[0];
switch (match[0]) {
case "for":
case "if":
case "while":
case "with":
if (lastSignificantToken !== "." && lastSignificantToken !== "?.") {
nextLastSignificantToken = TOK_NonExpressionParenKeyword;
}
}
lastSignificantToken = nextLastSignificantToken;
postfixIncDec = !KeywordsWithExpressionAfter.test(match[0]);
yield ({
type: TYPE_IdentifierName,
value: match[0]
});
continue;
}
StringLiteral.lastIndex = lastIndex;
if (match = StringLiteral.exec(input)) {
lastIndex = StringLiteral.lastIndex;
lastSignificantToken = match[0];
postfixIncDec = true;
yield ({
type: TYPE_StringLiteral,
value: match[0],
closed: match[2] !== void 0
});
continue;
}
NumericLiteral.lastIndex = lastIndex;
if (match = NumericLiteral.exec(input)) {
lastIndex = NumericLiteral.lastIndex;
lastSignificantToken = match[0];
postfixIncDec = true;
yield ({
type: TYPE_NumericLiteral,
value: match[0]
});
continue;
}
Template.lastIndex = lastIndex;
if (match = Template.exec(input)) {
lastIndex = Template.lastIndex;
lastSignificantToken = match[0];
if (match[1] === "${") {
lastSignificantToken = TOK_InterpolationInTemplate;
stack.push({
tag: TAG_InterpolationInTemplate,
nesting: braces.length
});
postfixIncDec = false;
yield ({
type: TYPE_TemplateHead,
value: match[0]
});
} else {
postfixIncDec = true;
yield ({
type: TYPE_NoSubstitutionTemplate,
value: match[0],
closed: match[1] === "`"
});
}
continue;
}
break;
}
WhiteSpace.lastIndex = lastIndex;
if (match = WhiteSpace.exec(input)) {
lastIndex = WhiteSpace.lastIndex;
yield ({
type: TYPE_WhiteSpace,
value: match[0]
});
continue;
}
LineTerminatorSequence.lastIndex = lastIndex;
if (match = LineTerminatorSequence.exec(input)) {
lastIndex = LineTerminatorSequence.lastIndex;
postfixIncDec = false;
if (KeywordsWithNoLineTerminatorAfter.test(lastSignificantToken)) {
lastSignificantToken = TOK_NoLineTerminatorHere;
}
yield ({
type: TYPE_LineTerminatorSequence,
value: match[0]
});
continue;
}
MultiLineComment.lastIndex = lastIndex;
if (match = MultiLineComment.exec(input)) {
lastIndex = MultiLineComment.lastIndex;
if (Newline.test(match[0])) {
postfixIncDec = false;
if (KeywordsWithNoLineTerminatorAfter.test(lastSignificantToken)) {
lastSignificantToken = TOK_NoLineTerminatorHere;
}
}
yield ({
type: TYPE_MultiLineComment,
value: match[0],
closed: match[1] !== void 0
});
continue;
}
SingleLineComment.lastIndex = lastIndex;
if (match = SingleLineComment.exec(input)) {
lastIndex = SingleLineComment.lastIndex;
postfixIncDec = false;
yield ({
type: TYPE_SingleLineComment,
value: match[0]
});
continue;
}
firstCodePoint = String.fromCodePoint(input.codePointAt(lastIndex));
lastIndex += firstCodePoint.length;
lastSignificantToken = firstCodePoint;
postfixIncDec = false;
yield ({
type: TYPE_Invalid,
value: firstCodePoint
});
}
return void 0;
}