(perf) cache lineoffsets when mapping between position/offset (#1311)

Author: dummdidumm

packages/language-server/src/lib/documents/Document.ts

@@ -69,6 +69,7 @@ export class Document extends WritableDocument {
     setText(text: string) {
         this.content = text;
         this.version++;
+        this.lineOffsets = undefined;
         this.updateDocInfo();
     }
 

packages/language-server/src/lib/documents/DocumentBase.ts

@@ -1,5 +1,5 @@
-import { clamp } from '../../utils';
 import { Position, TextDocument } from 'vscode-languageserver';
+import { getLineOffsets, offsetAt, positionAt } from './utils';
 
 /**
  * Represents a textual document.
@@ -25,6 +25,11 @@ export abstract class ReadableDocument implements TextDocument {
      */
     public version = 0;
 
+    /**
+     * Should be cleared when there's an update to the text
+     */
+    protected lineOffsets?: number[];
+
     /**
      * Get the length of the document's content
      */
@@ -37,74 +42,22 @@ export abstract class ReadableDocument implements TextDocument {
      * @param offset The index of the position
      */
     positionAt(offset: number): Position {
-        offset = clamp(offset, 0, this.getTextLength());
-
-        const lineOffsets = this.getLineOffsets();
-        let low = 0;
-        let high = lineOffsets.length;
-        if (high === 0) {
-            return Position.create(0, offset);
-        }
-
-        while (low < high) {
-            const mid = Math.floor((low + high) / 2);
-            if (lineOffsets[mid] > offset) {
-                high = mid;
-            } else {
-                low = mid + 1;
-            }
-        }
-
-        // low is the least x for which the line offset is larger than the current offset
-        // or array.length if no line offset is larger than the current offset
-        const line = low - 1;
-        return Position.create(line, offset - lineOffsets[line]);
+        return positionAt(offset, this.getText(), this.getLineOffsets());
     }
 
     /**
      * Get the index of the line and character position
      * @param position Line and character position
      */
     offsetAt(position: Position): number {
-        const lineOffsets = this.getLineOffsets();
-
-        if (position.line >= lineOffsets.length) {
-            return this.getTextLength();
-        } else if (position.line < 0) {
-            return 0;
-        }
-
-        const lineOffset = lineOffsets[position.line];
-        const nextLineOffset =
-            position.line + 1 < lineOffsets.length
-                ? lineOffsets[position.line + 1]
-                : this.getTextLength();
-
-        return clamp(nextLineOffset, lineOffset, lineOffset + position.character);
+        return offsetAt(position, this.getText(), this.getLineOffsets());
     }
 
     private getLineOffsets() {
-        const lineOffsets = [];
-        const text = this.getText();
-        let isLineStart = true;
-
-        for (let i = 0; i < text.length; i++) {
-            if (isLineStart) {
-                lineOffsets.push(i);
-                isLineStart = false;
-            }
-            const ch = text.charAt(i);
-            isLineStart = ch === '\r' || ch === '\n';
-            if (ch === '\r' && i + 1 < text.length && text.charAt(i + 1) === '\n') {
-                i++;
-            }
-        }
-
-        if (isLineStart && text.length > 0) {
-            lineOffsets.push(text.length);
+        if (!this.lineOffsets) {
+            this.lineOffsets = getLineOffsets(this.getText());
         }
-
-        return lineOffsets;
+        return this.lineOffsets;
     }
 
     /**
@@ -126,7 +79,8 @@ export abstract class ReadableDocument implements TextDocument {
  */
 export abstract class WritableDocument extends ReadableDocument {
     /**
-     * Set the text content of the document
+     * Set the text content of the document.
+     * Implementers should set `lineOffsets` to `undefined` here.
      * @param text The new text content
      */
     abstract setText(text: string): void;
@@ -138,6 +92,7 @@ export abstract class WritableDocument extends ReadableDocument {
      * @param end End offset of the new text
      */
     update(text: string, start: number, end: number): void {
+        this.lineOffsets = undefined;
         const content = this.getText();
         this.setText(content.slice(0, start) + text + content.slice(end));
     }

packages/language-server/src/lib/documents/DocumentMapper.ts

@@ -13,7 +13,7 @@ import {
     TextEdit,
     InsertReplaceEdit
 } from 'vscode-languageserver';
-import { TagInformation, offsetAt, positionAt } from './utils';
+import { TagInformation, offsetAt, positionAt, getLineOffsets } from './utils';
 import { SourceMapConsumer } from 'source-map';
 import { Logger } from '../../logger';
 
@@ -90,28 +90,35 @@ export class IdentityMapper implements DocumentMapper {
  * Maps positions in a fragment relative to a parent.
  */
 export class FragmentMapper implements DocumentMapper {
+    private lineOffsetsOriginal = getLineOffsets(this.originalText);
+    private lineOffsetsGenerated = getLineOffsets(this.tagInfo.content);
+
     constructor(
         private originalText: string,
         private tagInfo: TagInformation,
         private url: string
     ) {}
 
     getOriginalPosition(generatedPosition: Position): Position {
-        const parentOffset = this.offsetInParent(offsetAt(generatedPosition, this.tagInfo.content));
-        return positionAt(parentOffset, this.originalText);
+        const parentOffset = this.offsetInParent(
+            offsetAt(generatedPosition, this.tagInfo.content, this.lineOffsetsGenerated)
+        );
+        return positionAt(parentOffset, this.originalText, this.lineOffsetsOriginal);
     }
 
     private offsetInParent(offset: number): number {
         return this.tagInfo.start + offset;
     }
 
     getGeneratedPosition(originalPosition: Position): Position {
-        const fragmentOffset = offsetAt(originalPosition, this.originalText) - this.tagInfo.start;
-        return positionAt(fragmentOffset, this.tagInfo.content);
+        const fragmentOffset =
+            offsetAt(originalPosition, this.originalText, this.lineOffsetsOriginal) -
+            this.tagInfo.start;
+        return positionAt(fragmentOffset, this.tagInfo.content, this.lineOffsetsGenerated);
     }
 
     isInGenerated(pos: Position): boolean {
-        const offset = offsetAt(pos, this.originalText);
+        const offset = offsetAt(pos, this.originalText, this.lineOffsetsOriginal);
         return offset >= this.tagInfo.start && offset <= this.tagInfo.end;
     }
 

packages/language-server/src/lib/documents/utils.ts

@@ -172,23 +172,31 @@ export function extractTemplateTag(source: string, html?: HTMLDocument): TagInfo
  * Get the line and character based on the offset
  * @param offset The index of the position
  * @param text The text for which the position should be retrived
+ * @param lineOffsets number Array with offsets for each line. Computed if not given
  */
-export function positionAt(offset: number, text: string): Position {
+export function positionAt(
+    offset: number,
+    text: string,
+    lineOffsets = getLineOffsets(text)
+): Position {
     offset = clamp(offset, 0, text.length);
 
-    const lineOffsets = getLineOffsets(text);
     let low = 0;
     let high = lineOffsets.length;
     if (high === 0) {
         return Position.create(0, offset);
     }
 
-    while (low < high) {
+    while (low <= high) {
         const mid = Math.floor((low + high) / 2);
-        if (lineOffsets[mid] > offset) {
-            high = mid;
-        } else {
+        const lineOffset = lineOffsets[mid];
+
+        if (lineOffset === offset) {
+            return Position.create(mid, 0);
+        } else if (offset > lineOffset) {
             low = mid + 1;
+        } else {
+            high = mid - 1;
         }
     }
 
@@ -202,10 +210,13 @@ export function positionAt(offset: number, text: string): Position {
  * Get the offset of the line and character position
  * @param position Line and character position
  * @param text The text for which the offset should be retrived
+ * @param lineOffsets number Array with offsets for each line. Computed if not given
  */
-export function offsetAt(position: Position, text: string): number {
-    const lineOffsets = getLineOffsets(text);
-
+export function offsetAt(
+    position: Position,
+    text: string,
+    lineOffsets = getLineOffsets(text)
+): number {
     if (position.line >= lineOffsets.length) {
         return text.length;
     } else if (position.line < 0) {
@@ -219,7 +230,7 @@ export function offsetAt(position: Position, text: string): number {
     return clamp(nextLineOffset, lineOffset, lineOffset + position.character);
 }
 
-function getLineOffsets(text: string) {
+export function getLineOffsets(text: string) {
     const lineOffsets = [];
     let isLineStart = true;
 

packages/language-server/src/plugins/svelte/features/getCodeActions/getQuickfixes.ts

@@ -11,7 +11,12 @@ import {
     TextDocumentEdit,
     TextEdit
 } from 'vscode-languageserver';
-import { mapObjWithRangeToOriginal, offsetAt, positionAt } from '../../../../lib/documents';
+import {
+    getLineOffsets,
+    mapObjWithRangeToOriginal,
+    offsetAt,
+    positionAt
+} from '../../../../lib/documents';
 import { getIndent, pathToUrl } from '../../../../utils';
 import { SvelteDocument } from '../../SvelteDocument';
 import ts from 'typescript';
@@ -89,26 +94,28 @@ async function getSvelteIgnoreEdit(svelteDoc: SvelteDocument, ast: Ast, diagnost
     } = diagnostic;
     const transpiled = await svelteDoc.getTranspiled();
     const content = transpiled.getText();
+    const lineOffsets = getLineOffsets(content);
     const { html } = ast;
     const generatedStart = transpiled.getGeneratedPosition(start);
     const generatedEnd = transpiled.getGeneratedPosition(end);
 
-    const diagnosticStartOffset = offsetAt(generatedStart, transpiled.getText());
-    const diagnosticEndOffset = offsetAt(generatedEnd, transpiled.getText());
+    const diagnosticStartOffset = offsetAt(generatedStart, content, lineOffsets);
+    const diagnosticEndOffset = offsetAt(generatedEnd, content, lineOffsets);
     const offsetRange: ts.TextRange = {
         pos: diagnosticStartOffset,
         end: diagnosticEndOffset
     };
 
     const node = findTagForRange(html, offsetRange);
 
-    const nodeStartPosition = positionAt(node.start, content);
+    const nodeStartPosition = positionAt(node.start, content, lineOffsets);
     const nodeLineStart = offsetAt(
         {
             line: nodeStartPosition.line,
             character: 0
         },
-        transpiled.getText()
+        content,
+        lineOffsets
     );
     const afterStartLineStart = content.slice(nodeLineStart);
     const indent = getIndent(afterStartLineStart);

packages/language-server/src/plugins/typescript/DocumentSnapshot.ts

@@ -10,7 +10,8 @@ import {
     offsetAt,
     positionAt,
     TagInformation,
-    isInTag
+    isInTag,
+    getLineOffsets
 } from '../../lib/documents';
 import { pathToUrl } from '../../utils';
 import { ConsumerDocumentMapper } from './DocumentMapper';
@@ -313,6 +314,7 @@ export class JSOrTSDocumentSnapshot
 {
     scriptKind = getScriptKindFromFileName(this.filePath);
     scriptInfo = null;
+    private lineOffsets?: number[];
 
     constructor(public version: number, public readonly filePath: string, private text: string) {
         super(pathToUrl(filePath));
@@ -335,11 +337,11 @@ export class JSOrTSDocumentSnapshot
     }
 
     positionAt(offset: number) {
-        return positionAt(offset, this.text);
+        return positionAt(offset, this.text, this.getLineOffsets());
     }
 
     offsetAt(position: Position): number {
-        return offsetAt(position, this.text);
+        return offsetAt(position, this.text, this.getLineOffsets());
     }
 
     async getFragment() {
@@ -365,6 +367,14 @@ export class JSOrTSDocumentSnapshot
         }
 
         this.version++;
+        this.lineOffsets = undefined;
+    }
+
+    private getLineOffsets() {
+        if (!this.lineOffsets) {
+            this.lineOffsets = getLineOffsets(this.text);
+        }
+        return this.lineOffsets;
     }
 }
 
@@ -373,6 +383,8 @@ export class JSOrTSDocumentSnapshot
  * to generated snapshot positions and vice versa.
  */
 export class SvelteSnapshotFragment implements SnapshotFragment {
+    private lineOffsets = getLineOffsets(this.text);
+
     constructor(
         private readonly mapper: DocumentMapper,
         public readonly text: string,
@@ -409,11 +421,11 @@ export class SvelteSnapshotFragment implements SnapshotFragment {
     }
 
     positionAt(offset: number) {
-        return positionAt(offset, this.text);
+        return positionAt(offset, this.text, this.lineOffsets);
     }
 
     offsetAt(position: Position) {
-        return offsetAt(position, this.text);
+        return offsetAt(position, this.text, this.lineOffsets);
     }
 
     /**