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Fix parser TODO #49679

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Merged
merged 1 commit into from
Jun 27, 2022
Merged

Fix parser TODO #49679

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25 changes: 10 additions & 15 deletions src/compiler/parser.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -2449,7 +2449,7 @@ namespace ts {
return parseElement();
}

function currentNode(parsingContext: ParsingContext): Node | undefined {
function currentNode(parsingContext: ParsingContext, pos?: number): Node | undefined {
// If we don't have a cursor or the parsing context isn't reusable, there's nothing to reuse.
//
// If there is an outstanding parse error that we've encountered, but not attached to
Expand All @@ -2463,7 +2463,7 @@ namespace ts {
return undefined;
}

const node = syntaxCursor.currentNode(scanner.getStartPos());
const node = syntaxCursor.currentNode(pos ?? scanner.getStartPos());

// Can't reuse a missing node.
// Can't reuse a node that intersected the change range.
Expand Down Expand Up @@ -6610,25 +6610,20 @@ namespace ts {
}

function parseDeclaration(): Statement {
// TODO: Can we hold onto the parsed decorators/modifiers and advance the scanner
// if we can't reuse the declaration, so that we don't do this work twice?
//
// `parseListElement` attempted to get the reused node at this position,
// but the ambient context flag was not yet set, so the node appeared
// not reusable in that context.
const isAmbient = some(lookAhead(() => (parseDecorators(), parseModifiers())), isDeclareModifier);
if (isAmbient) {
const node = tryReuseAmbientDeclaration();
if (node) {
return node;
}
}

const pos = getNodePos();
const hasJSDoc = hasPrecedingJSDocComment();
const decorators = parseDecorators();
const modifiers = parseModifiers();
const isAmbient = some(modifiers, isDeclareModifier);
if (isAmbient) {
const node = tryReuseAmbientDeclaration(pos);
if (node) {
return node;
}

for (const m of modifiers!) {
(m as Mutable<Node>).flags |= NodeFlags.Ambient;
}
Expand All @@ -6639,9 +6634,9 @@ namespace ts {
}
}

function tryReuseAmbientDeclaration(): Statement | undefined {
function tryReuseAmbientDeclaration(pos: number): Statement | undefined {
return doInsideOfContext(NodeFlags.Ambient, () => {
const node = currentNode(parsingContext);
const node = currentNode(parsingContext, pos);
if (node) {
return consumeNode(node) as Statement;
}
Expand Down