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refactor(parse): Use switch for parsing
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And make the loop terminate as we reach the end

BREAKING: An empty selector will now return an empty array, instead of an array containing only an empty array.
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@fb55
fb55 committed Dec 25, 2021
1 parent 552d8d2 commit 7b6cc76
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Showing 2 changed files with 138 additions and 90 deletions.
6 changes: 3 additions & 3 deletions src/__fixtures__/out.json
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Original file line number Diff line number Diff line change
@@ -1,6 +1,6 @@
{
"": [[]],
"\t": [[]],
"": [],
"\t": [],
"\t#qunit-fixture p": [
[
{
Expand Down Expand Up @@ -81,7 +81,7 @@
}
]
],
" ": [[]],
" ": [],
" #qunit-fixture p": [
[
{
Expand Down
222 changes: 135 additions & 87 deletions src/parse.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -18,7 +18,7 @@ const enum CharCode {
LeftSquareBracket = 91,
RightSquareBracket = 93,
Comma = 44,
Dot = 46,
Period = 46,
Colon = 58,
SingleQuote = 39,
DoubleQuote = 34,
Expand Down Expand Up @@ -57,18 +57,6 @@ const actionTypes = new Map<number, AttributeAction>([
[CharCode.Pipe, AttributeAction.Hyphen],
]);

const Traversals: Map<number, TraversalType> = new Map([
[CharCode.GreaterThan, SelectorType.Child],
[CharCode.LessThan, SelectorType.Parent],
[CharCode.Tilde, SelectorType.Sibling],
[CharCode.Plus, SelectorType.Adjacent],
]);

const attribSelectors: Map<number, [string, AttributeAction]> = new Map([
[CharCode.Hash, ["id", AttributeAction.Equals]],
[CharCode.Dot, ["class", AttributeAction.Element]],
]);

// Pseudos, whose data property is parsed as well.
const unpackPseudos = new Set([
"has",
Expand Down Expand Up @@ -217,7 +205,6 @@ function parseSelector(
selectorIndex: number
): number {
let tokens: Selector[] = [];
let sawWS = false;

function getName(offset: number): string {
const match = selector.slice(selectorIndex + offset).match(reName);
Expand All @@ -234,9 +221,14 @@ function parseSelector(
}

function stripWhitespace(offset: number) {
while (isWhitespace(selector.charCodeAt(selectorIndex + offset)))
offset++;
selectorIndex += offset;

while (
selectorIndex < selector.length &&
isWhitespace(selector.charCodeAt(selectorIndex))
) {
selectorIndex++;
}
}

function isEscaped(pos: number): boolean {
Expand All @@ -252,56 +244,112 @@ function parseSelector(
}
}

function addTraversal(type: TraversalType) {
if (
tokens.length > 0 &&
tokens[tokens.length - 1].type === SelectorType.Descendant
) {
tokens[tokens.length - 1].type = type;
return;
}

ensureNotTraversal();

tokens.push({ type });
}

function addSpecialAttribute(name: string, action: AttributeAction) {
tokens.push({
type: SelectorType.Attribute,
name,
action,
value: getName(1),
namespace: null,
// TODO: Add quirksMode option, which makes `ignoreCase` `true` for HTML.
ignoreCase: options.xmlMode ? null : false,
});
}

/**
* We have finished parsing the current part of the selector.
*
* Remove descendant tokens at the end if they exist,
* and return the last index, so that parsing can be
* picked up from here.
*/
function finalizeSubselector() {
if (
tokens.length &&
tokens[tokens.length - 1].type === SelectorType.Descendant
) {
tokens.pop();
}

if (tokens.length === 0) {
throw new Error("Empty sub-selector");
}

subselects.push(tokens);
}

stripWhitespace(0);

for (;;) {
if (selector.length === selectorIndex) {
return selectorIndex;
}

loop: while (selectorIndex < selector.length) {
const firstChar = selector.charCodeAt(selectorIndex);

if (isWhitespace(firstChar)) {
sawWS = true;
stripWhitespace(1);
} else if (Traversals.has(firstChar)) {
ensureNotTraversal();
tokens.push({ type: Traversals.get(firstChar)! });
sawWS = false;

stripWhitespace(1);
} else if (firstChar === CharCode.Comma) {
if (tokens.length === 0) {
throw new Error("Empty sub-selector");
switch (firstChar) {
// Whitespace
case CharCode.Space:
case CharCode.Tab:
case CharCode.NewLine:
case CharCode.FormFeed:
case CharCode.CarriageReturn: {
if (
tokens.length === 0 ||
tokens[0].type !== SelectorType.Descendant
) {
ensureNotTraversal();
tokens.push({ type: SelectorType.Descendant });
}

stripWhitespace(1);
break;
}
subselects.push(tokens);
tokens = [];
sawWS = false;
stripWhitespace(1);
} else if (selector.startsWith("/*", selectorIndex)) {
const endIndex = selector.indexOf("*/", selectorIndex + 2);

if (endIndex < 0) {
throw new Error("Comment was not terminated");
// Traversals
case CharCode.GreaterThan: {
addTraversal(SelectorType.Child);
stripWhitespace(1);
break;
}

selectorIndex = endIndex + 2;
} else {
if (sawWS) {
ensureNotTraversal();
tokens.push({ type: SelectorType.Descendant });
sawWS = false;
case CharCode.LessThan: {
addTraversal(SelectorType.Parent);
stripWhitespace(1);
break;
}

const attribSelector = attribSelectors.get(firstChar);
if (attribSelector) {
const [name, action] = attribSelector;
tokens.push({
type: SelectorType.Attribute,
name,
action,
value: getName(1),
namespace: null,
// TODO: Add quirksMode option, which makes `ignoreCase` `true` for HTML.
ignoreCase: options.xmlMode ? null : false,
});
} else if (firstChar === CharCode.LeftSquareBracket) {
case CharCode.Tilde: {
addTraversal(SelectorType.Sibling);
stripWhitespace(1);
break;
}
case CharCode.Plus: {
addTraversal(SelectorType.Adjacent);
stripWhitespace(1);
break;
}
// Special attribute selectors: .class, #id
case CharCode.Period: {
addSpecialAttribute("class", AttributeAction.Element);
break;
}
case CharCode.Hash: {
addSpecialAttribute("id", AttributeAction.Equals);
break;
}
case CharCode.LeftSquareBracket: {
stripWhitespace(1);

// Determine attribute name and namespace
Expand Down Expand Up @@ -445,7 +493,9 @@ function parseSelector(
};

tokens.push(attributeSelector);
} else if (firstChar === CharCode.Colon) {
break;
}
case CharCode.Colon: {
if (selector.charCodeAt(selectorIndex + 1) === CharCode.Colon) {
tokens.push({
type: SelectorType.PseudoElement,
Expand Down Expand Up @@ -533,35 +583,38 @@ function parseSelector(
}

tokens.push({ type: SelectorType.Pseudo, name, data });
} else {
break;
}
case CharCode.Comma: {
finalizeSubselector();
tokens = [];
stripWhitespace(1);
break;
}
default: {
if (selector.startsWith("/*", selectorIndex)) {
const endIndex = selector.indexOf("*/", selectorIndex + 2);

if (endIndex < 0) {
throw new Error("Comment was not terminated");
}

selectorIndex = endIndex + 2;
break;
}

let namespace = null;
let name: string;

if (firstChar === CharCode.Asterisk) {
selectorIndex += 1;
name = "*";
} else if (firstChar === CharCode.Pipe) {
name = "";
} else if (reName.test(selector.slice(selectorIndex))) {
if (selector.charCodeAt(selectorIndex) === CharCode.Pipe) {
namespace = "";
selectorIndex += 1;
}
name = getName(0);
} else {
/*
* We have finished parsing the selector.
* Remove descendant tokens at the end if they exist,
* and return the last index, so that parsing can be
* picked up from here.
*/
if (
tokens.length &&
tokens[tokens.length - 1].type ===
SelectorType.Descendant
) {
tokens.pop();
}
addToken(subselects, tokens);
return selectorIndex;
break loop;
}

if (selector.charCodeAt(selectorIndex) === CharCode.Pipe) {
Expand Down Expand Up @@ -589,12 +642,7 @@ function parseSelector(
}
}
}
}

function addToken(subselects: Selector[][], tokens: Selector[]) {
if (subselects.length > 0 && tokens.length === 0) {
throw new Error("Empty sub-selector");
}

subselects.push(tokens);
finalizeSubselector();
return selectorIndex;
}

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