Skip to content

Commit

Permalink
refactor(parse): Walk through selector using indices
Browse files Browse the repository at this point in the history 
We no longer rely as much on updated string slices, which should reduce the number of allocations. Also, this allows us to add token ranges in a next step.
  • Loading branch information
@fb55
fb55 committed Oct 12, 2020
1 parent c49747f commit c667214
Showing 1 changed file with 54 additions and 46 deletions.
100 changes: 54 additions & 46 deletions src/parse.ts
View file
Original file line number Diff line number Diff line change
Expand Up @@ -170,9 +170,9 @@ export default function parse(
): Selector[][] {
const subselects: Selector[][] = [];

selector = parseSelector(subselects, `${selector}`, options);
const endIndex = parseSelector(subselects, `${selector}`, options, 0);

if (selector !== "") {
if (endIndex < selector.length) {
throw new Error(`Unmatched selector: ${selector}`);
}

Expand All @@ -182,26 +182,29 @@ export default function parse(
function parseSelector(
subselects: Selector[][],
selector: string,
options: Options = {}
): string {
options: Options = {},
selectorIndex: number
): number {
let tokens: Selector[] = [];
let sawWS = false;

function getName(): string {
const match = selector.match(reName);
function getName(offset: number): string {
const match = selector.slice(selectorIndex + offset).match(reName);

if (!match) {
throw new Error(`Expected name, found ${selector}`);
throw new Error(
`Expected name, found ${selector.slice(selectorIndex)}`
);
}

const [sub] = match;
selector = selector.substr(sub.length);
return unescapeCSS(sub);
const [name] = match;
selectorIndex += offset + name.length;
return unescapeCSS(name);
}

function stripWhitespace(start: number) {
while (isWhitespace(selector.charAt(start))) start++;
selector = selector.substr(start);
function stripWhitespace(offset: number) {
while (isWhitespace(selector.charAt(selectorIndex + offset))) offset++;
selectorIndex += offset;
}

function isEscaped(pos: number): boolean {
Expand All @@ -220,7 +223,7 @@ function parseSelector(
stripWhitespace(0);

while (selector !== "") {
const firstChar = selector.charAt(0);
const firstChar = selector.charAt(selectorIndex);

if (isWhitespace(firstChar)) {
sawWS = true;
Expand All @@ -247,21 +250,22 @@ function parseSelector(
}

if (firstChar === "*") {
selector = selector.substr(1);
selectorIndex += 1;
tokens.push({ type: "universal" });
} else if (firstChar in attribSelectors) {
const [name, action] = attribSelectors[firstChar];
selector = selector.substr(1);
tokens.push({
type: "attribute",
name,
action,
value: getName(),
value: getName(1),
ignoreCase: false,
});
} else if (firstChar === "[") {
selector = selector.substr(1);
const attributeMatch = selector.match(reAttr);
const attributeMatch = selector
.slice(selectorIndex + 1)
.match(reAttr);

if (!attributeMatch) {
throw new Error(
`Malformed attribute selector: ${selector}`
Expand All @@ -278,7 +282,7 @@ function parseSelector(
ignoreCase,
] = attributeMatch;

selector = selector.substr(completeSelector.length);
selectorIndex += completeSelector.length + 1;
let name = unescapeCSS(baseName);

if (options.lowerCaseAttributeNames ?? !options.xmlMode) {
Expand All @@ -293,53 +297,58 @@ function parseSelector(
ignoreCase: !!ignoreCase,
});
} else if (firstChar === ":") {
if (selector.charAt(1) === ":") {
selector = selector.substr(2);
if (selector.charAt(selectorIndex + 1) === ":") {
tokens.push({
type: "pseudo-element",
name: getName().toLowerCase(),
name: getName(2).toLowerCase(),
});
continue;
}

selector = selector.substr(1);

const name = getName().toLowerCase();
const name = getName(1).toLowerCase();
let data: DataType = null;

if (selector.startsWith("(")) {
if (selector.charAt(selectorIndex) === "(") {
if (unpackPseudos.has(name)) {
if (quotes.has(selector.charAt(1))) {
if (quotes.has(selector.charAt(selectorIndex + 1))) {
throw new Error(
`Pseudo-selector ${name} cannot be quoted`
);
}

selector = selector.substr(1);

data = [];
selector = parseSelector(data, selector, options);

if (!selector.startsWith(")")) {
selectorIndex = parseSelector(
data,
selector,
options,
selectorIndex + 1
);

if (selector.charAt(selectorIndex) !== ")") {
throw new Error(
`Missing closing parenthesis in :${name} (${selector})`
);
}

selector = selector.substr(1);
selectorIndex += 1;
} else {
let pos = 1;
selectorIndex += 1;
const start = selectorIndex;
let counter = 1;

for (; counter > 0 && pos < selector.length; pos++) {
for (
;
counter > 0 && selectorIndex < selector.length;
selectorIndex++
) {
if (
selector.charAt(pos) === "(" &&
!isEscaped(pos)
selector.charAt(selectorIndex) === "(" &&
!isEscaped(selectorIndex)
) {
counter++;
} else if (
selector.charAt(pos) === ")" &&
!isEscaped(pos)
selector.charAt(selectorIndex) === ")" &&
!isEscaped(selectorIndex)
) {
counter--;
}
Expand All @@ -349,8 +358,7 @@ function parseSelector(
throw new Error("Parenthesis not matched");
}

data = selector.substr(1, pos - 2);
selector = selector.substr(pos);
data = selector.slice(start, selectorIndex - 1);

if (stripQuotesFromPseudos.has(name)) {
const quot = data.charAt(0);
Expand All @@ -365,8 +373,8 @@ function parseSelector(
}

tokens.push({ type: "pseudo", name, data });
} else if (reName.test(selector)) {
let name = getName();
} else if (reName.test(selector.slice(selectorIndex))) {
let name = getName(0);

if (options.lowerCaseTags ?? !options.xmlMode) {
name = name.toLowerCase();
Expand All @@ -381,14 +389,14 @@ function parseSelector(
tokens.pop();
}
addToken(subselects, tokens);
return selector;
return selectorIndex;
}
}
}

addToken(subselects, tokens);

return selector;
return selectorIndex;
}

function addToken(subselects: Selector[][], tokens: Selector[]) {
Expand Down

0 comments on commit c667214

Please sign in to comment.