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Merge pull request #10782 from Microsoft/react_whitespace

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For JSX text, construct a single literal node `"foo bar"` instead of `"foo" + " " + "bar"`
This commit is contained in:
Andy
2017-01-05 13:55:42 -08:00
committed by GitHub
parent 1978c5b07d 2248c984b3
commit 91af4ae6b3
5 changed files with 116 additions and 46 deletions
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86
src/compiler/transformers/jsx.ts
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@@ -160,33 +160,50 @@ namespace ts {
}
}
function visitJsxText(node: JsxText) {
const text = getTextOfNode(node, /*includeTrivia*/ true);
let parts: Expression[];
let firstNonWhitespace = 0;
let lastNonWhitespace = -1;
function visitJsxText(node: JsxText): StringLiteral | undefined {
const fixed = fixupWhitespaceAndDecodeEntities(getTextOfNode(node, /*includeTrivia*/ true));
return fixed === undefined ? undefined : createLiteral(fixed);
}
/**
* JSX trims whitespace at the end and beginning of lines, except that the
* start/end of a tag is considered a start/end of a line only if that line is
* on the same line as the closing tag. See examples in
* tests/cases/conformance/jsx/tsxReactEmitWhitespace.tsx
* See also https://www.w3.org/TR/html4/struct/text.html#h-9.1 and https://www.w3.org/TR/CSS2/text.html#white-space-model
*
* An equivalent algorithm would be:
* - If there is only one line, return it.
* - If there is only whitespace (but multiple lines), return `undefined`.
* - Split the text into lines.
* - 'trimRight' the first line, 'trimLeft' the last line, 'trim' middle lines.
* - Decode entities on each line (individually).
* - Remove empty lines and join the rest with " ".
*/
function fixupWhitespaceAndDecodeEntities(text: string): string | undefined {
let acc: string | undefined;
// First non-whitespace character on this line.
let firstNonWhitespace = 0;
// Last non-whitespace character on this line.
let lastNonWhitespace = -1;
// These initial values are special because the first line is:
// firstNonWhitespace = 0 to indicate that we want leading whitsepace,
// but lastNonWhitespace = -1 as a special flag to indicate that we *don't* include the line if it's all whitespace.
// JSX trims whitespace at the end and beginning of lines, except that the
// start/end of a tag is considered a start/end of a line only if that line is
// on the same line as the closing tag. See examples in
// tests/cases/conformance/jsx/tsxReactEmitWhitespace.tsx
for (let i = 0; i < text.length; i++) {
const c = text.charCodeAt(i);
if (isLineBreak(c)) {
if (firstNonWhitespace !== -1 && (lastNonWhitespace - firstNonWhitespace + 1 > 0)) {
const part = text.substr(firstNonWhitespace, lastNonWhitespace - firstNonWhitespace + 1);
if (!parts) {
parts = [];
}
// We do not escape the string here as that is handled by the printer
// when it emits the literal. We do, however, need to decode JSX entities.
parts.push(createLiteral(decodeEntities(part)));
// If we've seen any non-whitespace characters on this line, add the 'trim' of the line.
// (lastNonWhitespace === -1 is a special flag to detect whether the first line is all whitespace.)
if (firstNonWhitespace !== -1 && lastNonWhitespace !== -1) {
acc = addLineOfJsxText(acc, text.substr(firstNonWhitespace, lastNonWhitespace - firstNonWhitespace + 1));
}
// Reset firstNonWhitespace for the next line.
// Don't bother to reset lastNonWhitespace because we ignore it if firstNonWhitespace = -1.
firstNonWhitespace = -1;
}
else if (!isWhiteSpace(c)) {
else if (!isWhiteSpaceSingleLine(c)) {
lastNonWhitespace = i;
if (firstNonWhitespace === -1) {
firstNonWhitespace = i;
@@ -194,29 +211,18 @@ namespace ts {
}
}
if (firstNonWhitespace !== -1) {
const part = text.substr(firstNonWhitespace);
if (!parts) {
parts = [];
}
// We do not escape the string here as that is handled by the printer
// when it emits the literal. We do, however, need to decode JSX entities.
parts.push(createLiteral(decodeEntities(part)));
}
if (parts) {
return reduceLeft(parts, aggregateJsxTextParts);
}
return undefined;
return firstNonWhitespace !== -1
// Last line had a non-whitespace character. Emit the 'trimLeft', meaning keep trailing whitespace.
? addLineOfJsxText(acc, text.substr(firstNonWhitespace))
// Last line was all whitespace, so ignore it
: acc;
}
/**
* Aggregates two expressions by interpolating them with a whitespace literal.
*/
function aggregateJsxTextParts(left: Expression, right: Expression) {
return createAdd(createAdd(left, createLiteral(" ")), right);
function addLineOfJsxText(acc: string | undefined, trimmedLine: string): string {
// We do not escape the string here as that is handled by the printer
// when it emits the literal. We do, however, need to decode JSX entities.
const decoded = decodeEntities(trimmedLine);
return acc === undefined ? decoded : acc + " " + decoded;
}
/**