Add method on host to get DocumentPositionMapper so it can be cached.

src/server/project.ts

@@ -503,6 +503,66 @@ namespace ts.server {
             return this.getLanguageService().getSourceMapper();
         }
 
+        /*@internal*/
+        getDocumentPositionMapper(fileName: string): DocumentPositionMapper | undefined {
+            const declarationInfo = this.projectService.getOrCreateScriptInfoNotOpenedByClient(fileName, this.currentDirectory, this.directoryStructureHost);
+            if (!declarationInfo) return undefined;
+
+            declarationInfo.getSnapshot(); // Ensure synchronized
+            const existingMapper = declarationInfo.textStorage.mapper;
+            if (existingMapper !== undefined) {
+                return existingMapper ? existingMapper : undefined;
+            }
+
+            // Create the mapper
+            declarationInfo.mapInfo = undefined;
+
+            const mapper = getDocumentPositionMapper({
+                getCanonicalFileName: this.projectService.toCanonicalFileName,
+                log: s => this.log(s),
+                readMapFile: f => this.readMapFile(f, declarationInfo),
+                getSourceFileLike: f => this.getSourceFileLike(f)
+            }, declarationInfo.fileName, declarationInfo.textStorage.getLineInfo());
+            declarationInfo.textStorage.mapper = mapper || false;
+            return mapper;
+        }
+
+        private readMapFile(fileName: string, declarationInfo: ScriptInfo) {
+            const mapInfo = this.projectService.getOrCreateScriptInfoNotOpenedByClient(fileName, this.currentDirectory, this.directoryStructureHost);
+            if (!mapInfo) return undefined;
+            declarationInfo.mapInfo = mapInfo;
+            const snap = mapInfo.getSnapshot();
+            return snap.getText(0, snap.getLength());
+        }
+
+        /*@internal*/
+        getSourceFileLike(fileName: string) {
+            const path = this.toPath(fileName);
+            const sourceFile = this.getSourceFile(path);
+            if (sourceFile && sourceFile.resolvedPath === path) return sourceFile;
+
+            // Need to look for other files.
+            const info = this.projectService.getOrCreateScriptInfoNotOpenedByClient(fileName, this.currentDirectory, this.directoryStructureHost);
+            if (!info) return undefined;
+
+            // Key doesnt matter since its only for text and lines
+            if (info.cacheSourceFile) return info.cacheSourceFile.sourceFile;
+            if (info.textStorage.sourceFileLike) return info.textStorage.sourceFileLike;
+
+            info.textStorage.sourceFileLike = {
+                get text() {
+                    Debug.fail("shouldnt need text");
+                    return "";
+                },
+                getLineAndCharacterOfPosition: pos => {
+                    const lineOffset = info.positionToLineOffset(pos);
+                    return { line: lineOffset.line - 1, character: lineOffset.offset - 1 };
+                },
+                getPositionOfLineAndCharacter: (line, character) => info.lineOffsetToPosition(line + 1, character + 1)
+            };
+            return info.textStorage.sourceFileLike;
+        }
+
         private shouldEmitFile(scriptInfo: ScriptInfo) {
             return scriptInfo && !scriptInfo.isDynamicOrHasMixedContent();
         }

src/server/scriptInfo.ts

@@ -46,6 +46,9 @@ namespace ts.server {
          */
         private pendingReloadFromDisk = false;
 
+        mapper: DocumentPositionMapper | false | undefined = false;
+        sourceFileLike: SourceFileLike | undefined;
+
         constructor(private readonly host: ServerHost, private readonly fileName: NormalizedPath, initialVersion: ScriptInfoVersion | undefined, private readonly info: ScriptInfo) {
             this.version = initialVersion || { svc: 0, text: 0 };
         }
@@ -70,6 +73,8 @@ namespace ts.server {
             this.text = newText;
             this.lineMap = undefined;
             this.fileSize = undefined;
+            this.mapper = undefined;
+            this.sourceFileLike = undefined;
             this.version.text++;
         }
 
@@ -79,6 +84,8 @@ namespace ts.server {
             this.text = undefined;
             this.lineMap = undefined;
             this.fileSize = undefined;
+            this.mapper = undefined;
+            this.sourceFileLike = undefined;
         }
 
         /**
@@ -156,8 +163,8 @@ namespace ts.server {
                 : ScriptSnapshot.fromString(this.getOrLoadText());
         }
 
-        public getLineInfo(line: number): AbsolutePositionAndLineText {
-            return this.switchToScriptVersionCache().getLineInfo(line);
+        public getAbsolutePositionAndLineText(line: number): AbsolutePositionAndLineText {
+            return this.switchToScriptVersionCache().getAbsolutePositionAndLineText(line);
         }
         /**
          *  @param line 0 based index
@@ -246,6 +253,17 @@ namespace ts.server {
             Debug.assert(!this.svc, "ScriptVersionCache should not be set");
             return this.lineMap || (this.lineMap = computeLineStarts(this.getOrLoadText()));
         }
+
+        getLineInfo(): LineInfo {
+            if (this.svc) {
+                return {
+                    getLineCount: () => this.svc!.getLineCount(),
+                    getLineText: line => this.svc!.getAbsolutePositionAndLineText(line + 1).lineText!
+                };
+            }
+            const lineMap = this.getLineMap();
+            return getLineInfo(this.text!, lineMap);
+        }
     }
 
     /*@internal*/
@@ -269,7 +287,7 @@ namespace ts.server {
 
         /* @internal */
         fileWatcher: FileWatcher | undefined;
-        private textStorage: TextStorage;
+        /* @internal */ textStorage: TextStorage;
 
         /*@internal*/
         readonly isDynamic: boolean;
@@ -284,6 +302,9 @@ namespace ts.server {
         /*@internal*/
         mTime?: number;
 
+        /*@internal*/
+        mapInfo?: ScriptInfo;
+
         constructor(
             private readonly host: ServerHost,
             readonly fileName: NormalizedPath,
@@ -521,8 +542,8 @@ namespace ts.server {
         }
 
         /*@internal*/
-        getLineInfo(line: number): AbsolutePositionAndLineText {
-            return this.textStorage.getLineInfo(line);
+        getAbsolutePositionAndLineText(line: number): AbsolutePositionAndLineText {
+            return this.textStorage.getAbsolutePositionAndLineText(line);
         }
 
         editContent(start: number, end: number, newText: string): void {

src/server/scriptVersionCache.ts

@@ -308,8 +308,8 @@ namespace ts.server {
             return this._getSnapshot().version;
         }
 
-        getLineInfo(line: number): AbsolutePositionAndLineText {
-            return this._getSnapshot().index.lineNumberToInfo(line);
+        getAbsolutePositionAndLineText(oneBasedLine: number): AbsolutePositionAndLineText {
+            return this._getSnapshot().index.lineNumberToInfo(oneBasedLine);
         }
 
         lineOffsetToPosition(line: number, column: number): number {
@@ -348,6 +348,10 @@ namespace ts.server {
             }
         }
 
+        getLineCount() {
+            return this._getSnapshot().index.getLineCount();
+        }
+
         static fromString(script: string) {
             const svc = new ScriptVersionCache();
             const snap = new LineIndexSnapshot(0, svc, new LineIndex());
@@ -400,8 +404,12 @@ namespace ts.server {
             return this.root.charOffsetToLineInfo(1, position);
         }
 
+        getLineCount() {
+            return this.root.lineCount();
+        }
+
         lineNumberToInfo(oneBasedLine: number): AbsolutePositionAndLineText {
-            const lineCount = this.root.lineCount();
+            const lineCount = this.getLineCount();
             if (oneBasedLine <= lineCount) {
                 const { position, leaf } = this.root.lineNumberToInfo(oneBasedLine, 0);
                 return { absolutePosition: position, lineText: leaf && leaf.text };

src/server/session.ts

@@ -1474,7 +1474,7 @@ namespace ts.server {
             // only to the previous line.  If all this is true, then
             // add edits necessary to properly indent the current line.
             if ((args.key === "\n") && ((!edits) || (edits.length === 0) || allEditsBeforePos(edits, position))) {
-                const { lineText, absolutePosition } = scriptInfo.getLineInfo(args.line);
+                const { lineText, absolutePosition } = scriptInfo.getAbsolutePositionAndLineText(args.line);
                 if (lineText && lineText.search("\\S") < 0) {
                     const preferredIndent = languageService.getIndentationAtPosition(file, position, formatOptions);
                     let hasIndent = 0;