368 lines
10 KiB
JavaScript
368 lines
10 KiB
JavaScript
import {
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eat,
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finishToken,
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getTokenFromCode,
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IdentifierRole,
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JSXRole,
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match,
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next,
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skipSpace,
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Token,
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} from "../../tokenizer/index";
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import {TokenType as tt} from "../../tokenizer/types";
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import {input, isTypeScriptEnabled, state} from "../../traverser/base";
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import {parseExpression, parseMaybeAssign} from "../../traverser/expression";
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import {expect, unexpected} from "../../traverser/util";
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import {charCodes} from "../../util/charcodes";
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import {IS_IDENTIFIER_CHAR, IS_IDENTIFIER_START} from "../../util/identifier";
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import {tsTryParseJSXTypeArgument} from "../typescript";
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/**
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* Read token with JSX contents.
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*
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* In addition to detecting jsxTagStart and also regular tokens that might be
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* part of an expression, this code detects the start and end of text ranges
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* within JSX children. In order to properly count the number of children, we
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* distinguish jsxText from jsxEmptyText, which is a text range that simplifies
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* to the empty string after JSX whitespace trimming.
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*
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* It turns out that a JSX text range will simplify to the empty string if and
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* only if both of these conditions hold:
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* - The range consists entirely of whitespace characters (only counting space,
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* tab, \r, and \n).
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* - The range has at least one newline.
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* This can be proven by analyzing any implementation of whitespace trimming,
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* e.g. formatJSXTextLiteral in Sucrase or cleanJSXElementLiteralChild in Babel.
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*/
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function jsxReadToken() {
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let sawNewline = false;
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let sawNonWhitespace = false;
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while (true) {
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if (state.pos >= input.length) {
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unexpected("Unterminated JSX contents");
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return;
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}
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const ch = input.charCodeAt(state.pos);
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if (ch === charCodes.lessThan || ch === charCodes.leftCurlyBrace) {
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if (state.pos === state.start) {
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if (ch === charCodes.lessThan) {
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state.pos++;
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finishToken(tt.jsxTagStart);
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return;
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}
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getTokenFromCode(ch);
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return;
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}
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if (sawNewline && !sawNonWhitespace) {
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finishToken(tt.jsxEmptyText);
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} else {
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finishToken(tt.jsxText);
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}
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return;
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}
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// This is part of JSX text.
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if (ch === charCodes.lineFeed) {
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sawNewline = true;
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} else if (ch !== charCodes.space && ch !== charCodes.carriageReturn && ch !== charCodes.tab) {
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sawNonWhitespace = true;
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}
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state.pos++;
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}
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}
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function jsxReadString(quote) {
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state.pos++;
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for (;;) {
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if (state.pos >= input.length) {
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unexpected("Unterminated string constant");
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return;
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}
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const ch = input.charCodeAt(state.pos);
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if (ch === quote) {
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state.pos++;
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break;
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}
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state.pos++;
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}
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finishToken(tt.string);
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}
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// Read a JSX identifier (valid tag or attribute name).
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//
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// Optimized version since JSX identifiers can't contain
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// escape characters and so can be read as single slice.
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// Also assumes that first character was already checked
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// by isIdentifierStart in readToken.
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function jsxReadWord() {
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let ch;
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do {
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if (state.pos > input.length) {
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unexpected("Unexpectedly reached the end of input.");
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return;
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}
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ch = input.charCodeAt(++state.pos);
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} while (IS_IDENTIFIER_CHAR[ch] || ch === charCodes.dash);
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finishToken(tt.jsxName);
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}
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// Parse next token as JSX identifier
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function jsxParseIdentifier() {
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nextJSXTagToken();
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}
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// Parse namespaced identifier.
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function jsxParseNamespacedName(identifierRole) {
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jsxParseIdentifier();
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if (!eat(tt.colon)) {
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// Plain identifier, so this is an access.
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state.tokens[state.tokens.length - 1].identifierRole = identifierRole;
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return;
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}
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// Process the second half of the namespaced name.
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jsxParseIdentifier();
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}
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// Parses element name in any form - namespaced, member
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// or single identifier.
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function jsxParseElementName() {
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const firstTokenIndex = state.tokens.length;
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jsxParseNamespacedName(IdentifierRole.Access);
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let hadDot = false;
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while (match(tt.dot)) {
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hadDot = true;
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nextJSXTagToken();
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jsxParseIdentifier();
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}
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// For tags like <div> with a lowercase letter and no dots, the name is
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// actually *not* an identifier access, since it's referring to a built-in
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// tag name. Remove the identifier role in this case so that it's not
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// accidentally transformed by the imports transform when preserving JSX.
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if (!hadDot) {
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const firstToken = state.tokens[firstTokenIndex];
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const firstChar = input.charCodeAt(firstToken.start);
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if (firstChar >= charCodes.lowercaseA && firstChar <= charCodes.lowercaseZ) {
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firstToken.identifierRole = null;
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}
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}
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}
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// Parses any type of JSX attribute value.
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function jsxParseAttributeValue() {
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switch (state.type) {
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case tt.braceL:
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next();
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parseExpression();
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nextJSXTagToken();
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return;
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case tt.jsxTagStart:
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jsxParseElement();
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nextJSXTagToken();
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return;
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case tt.string:
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nextJSXTagToken();
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return;
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default:
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unexpected("JSX value should be either an expression or a quoted JSX text");
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}
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}
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// Parse JSX spread child, after already processing the {
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// Does not parse the closing }
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function jsxParseSpreadChild() {
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expect(tt.ellipsis);
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parseExpression();
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}
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// Parses JSX opening tag starting after "<".
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// Returns true if the tag was self-closing.
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// Does not parse the last token.
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function jsxParseOpeningElement(initialTokenIndex) {
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if (match(tt.jsxTagEnd)) {
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// This is an open-fragment.
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return false;
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}
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jsxParseElementName();
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if (isTypeScriptEnabled) {
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tsTryParseJSXTypeArgument();
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}
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let hasSeenPropSpread = false;
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while (!match(tt.slash) && !match(tt.jsxTagEnd) && !state.error) {
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if (eat(tt.braceL)) {
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hasSeenPropSpread = true;
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expect(tt.ellipsis);
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parseMaybeAssign();
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// }
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nextJSXTagToken();
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continue;
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}
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if (
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hasSeenPropSpread &&
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state.end - state.start === 3 &&
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input.charCodeAt(state.start) === charCodes.lowercaseK &&
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input.charCodeAt(state.start + 1) === charCodes.lowercaseE &&
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input.charCodeAt(state.start + 2) === charCodes.lowercaseY
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) {
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state.tokens[initialTokenIndex].jsxRole = JSXRole.KeyAfterPropSpread;
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}
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jsxParseNamespacedName(IdentifierRole.ObjectKey);
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if (match(tt.eq)) {
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nextJSXTagToken();
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jsxParseAttributeValue();
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}
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}
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const isSelfClosing = match(tt.slash);
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if (isSelfClosing) {
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// /
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nextJSXTagToken();
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}
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return isSelfClosing;
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}
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// Parses JSX closing tag starting after "</".
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// Does not parse the last token.
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function jsxParseClosingElement() {
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if (match(tt.jsxTagEnd)) {
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// Fragment syntax, so we immediately have a tag end.
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return;
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}
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jsxParseElementName();
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}
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// Parses entire JSX element, including its opening tag
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// (starting after "<"), attributes, contents and closing tag.
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// Does not parse the last token.
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function jsxParseElementAt() {
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const initialTokenIndex = state.tokens.length - 1;
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state.tokens[initialTokenIndex].jsxRole = JSXRole.NoChildren;
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let numExplicitChildren = 0;
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const isSelfClosing = jsxParseOpeningElement(initialTokenIndex);
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if (!isSelfClosing) {
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nextJSXExprToken();
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while (true) {
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switch (state.type) {
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case tt.jsxTagStart:
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nextJSXTagToken();
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if (match(tt.slash)) {
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nextJSXTagToken();
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jsxParseClosingElement();
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// Key after prop spread takes precedence over number of children,
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// since it means we switch to createElement, which doesn't care
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// about number of children.
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if (state.tokens[initialTokenIndex].jsxRole !== JSXRole.KeyAfterPropSpread) {
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if (numExplicitChildren === 1) {
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state.tokens[initialTokenIndex].jsxRole = JSXRole.OneChild;
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} else if (numExplicitChildren > 1) {
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state.tokens[initialTokenIndex].jsxRole = JSXRole.StaticChildren;
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}
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}
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return;
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}
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numExplicitChildren++;
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jsxParseElementAt();
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nextJSXExprToken();
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break;
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case tt.jsxText:
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numExplicitChildren++;
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nextJSXExprToken();
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break;
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case tt.jsxEmptyText:
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nextJSXExprToken();
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break;
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case tt.braceL:
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next();
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if (match(tt.ellipsis)) {
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jsxParseSpreadChild();
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nextJSXExprToken();
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// Spread children are a mechanism to explicitly mark children as
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// static, so count it as 2 children to satisfy the "more than one
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// child" condition.
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numExplicitChildren += 2;
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} else {
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// If we see {}, this is an empty pseudo-expression that doesn't
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// count as a child.
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if (!match(tt.braceR)) {
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numExplicitChildren++;
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parseExpression();
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}
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nextJSXExprToken();
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}
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break;
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// istanbul ignore next - should never happen
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default:
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unexpected();
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return;
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}
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}
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}
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}
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// Parses entire JSX element from current position.
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// Does not parse the last token.
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export function jsxParseElement() {
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nextJSXTagToken();
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jsxParseElementAt();
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}
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// ==================================
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// Overrides
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// ==================================
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export function nextJSXTagToken() {
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state.tokens.push(new Token());
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skipSpace();
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state.start = state.pos;
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const code = input.charCodeAt(state.pos);
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if (IS_IDENTIFIER_START[code]) {
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jsxReadWord();
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} else if (code === charCodes.quotationMark || code === charCodes.apostrophe) {
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jsxReadString(code);
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} else {
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// The following tokens are just one character each.
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++state.pos;
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switch (code) {
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case charCodes.greaterThan:
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finishToken(tt.jsxTagEnd);
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break;
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case charCodes.lessThan:
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finishToken(tt.jsxTagStart);
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break;
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case charCodes.slash:
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finishToken(tt.slash);
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break;
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case charCodes.equalsTo:
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finishToken(tt.eq);
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break;
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case charCodes.leftCurlyBrace:
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finishToken(tt.braceL);
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break;
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case charCodes.dot:
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finishToken(tt.dot);
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break;
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case charCodes.colon:
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finishToken(tt.colon);
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break;
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default:
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unexpected();
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}
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}
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}
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function nextJSXExprToken() {
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state.tokens.push(new Token());
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state.start = state.pos;
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jsxReadToken();
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}
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