CodeMapper support (#55406)

src/harness/client.ts

@@ -789,6 +789,8 @@ export class SessionClient implements LanguageService {
         });
     }
 
+    mapCode = notImplemented;
+
     private createFileLocationOrRangeRequestArgs(positionOrRange: number | TextRange, fileName: string): protocol.FileLocationOrRangeRequestArgs {
         return typeof positionOrRange === "number"
             ? this.createFileLocationRequestArgs(fileName, positionOrRange)

src/harness/fourslashImpl.ts

@@ -4510,6 +4510,57 @@ export class TestState {
 
         this.verifyCurrentFileContent(newFileContent);
     }
+
+    public baselineMapCode(
+        ranges: Range[][],
+        changes: string[] = [],
+    ): void {
+        const fileName = this.activeFile.fileName;
+        const focusLocations = ranges.map(r =>
+            r.map(({ pos, end }) => {
+                return { start: pos, length: end - pos };
+            })
+        );
+        let before = this.getFileContent(fileName);
+        const edits = this.languageService.mapCode(
+            fileName,
+            // We trim the leading whitespace stuff just so our test cases can be more readable.
+            changes,
+            focusLocations,
+            this.formatCodeSettings,
+            {},
+        );
+        this.applyChanges(edits);
+        focusLocations.forEach(r => {
+            r.sort((a, b) => a.start - b.start);
+        });
+        focusLocations.sort((a, b) => a[0].start - b[0].start);
+        for (const subLoc of focusLocations) {
+            for (const { start, length } of subLoc) {
+                let offset = 0;
+                for (const sl2 of focusLocations) {
+                    for (const { start: s2, length: l2 } of sl2) {
+                        if (s2 < start) {
+                            offset += 4;
+                            if ((s2 + l2) > start) {
+                                offset -= 2;
+                            }
+                        }
+                    }
+                }
+                before = before.slice(0, start + offset) + "[|" + before.slice(start + offset, start + offset + length) + "|]" + before.slice(start + offset + length);
+            }
+        }
+        const after = this.getFileContent(fileName);
+        const baseline = `
+// === ORIGINAL ===
+${before}
+// === INCOMING CHANGES ===
+${changes.join("\n// ---\n")}
+// === MAPPED ===
+${after}`;
+        this.baseline("mapCode", baseline, ".mapCode.ts");
+    }
 }
 
 function updateTextRangeForTextChanges({ pos, end }: ts.TextRange, textChanges: readonly ts.TextChange[]): ts.TextRange {

src/harness/fourslashInterfaceImpl.ts

@@ -239,6 +239,10 @@ export class VerifyNegatable {
     public uncommentSelection(newFileContent: string) {
         this.state.uncommentSelection(newFileContent);
     }
+
+    public baselineMapCode(ranges: FourSlash.Range[][], changes: string[] = []): void {
+        this.state.baselineMapCode(ranges, changes);
+    }
 }
 
 export class Verify extends VerifyNegatable {

src/server/protocol.ts

@@ -200,6 +200,7 @@ export const enum CommandTypes {
     ProvideCallHierarchyOutgoingCalls = "provideCallHierarchyOutgoingCalls",
     ProvideInlayHints = "provideInlayHints",
     WatchChange = "watchChange",
+    MapCode = "mapCode",
 }
 
 /**
@@ -2342,6 +2343,38 @@ export interface InlayHintsResponse extends Response {
     body?: InlayHintItem[];
 }
 
+export interface MapCodeRequestArgs extends FileRequestArgs {
+    /**
+     * The files and changes to try and apply/map.
+     */
+    mapping: MapCodeRequestDocumentMapping;
+}
+
+export interface MapCodeRequestDocumentMapping {
+    /**
+     * The specific code to map/insert/replace in the file.
+     */
+    contents: string[];
+
+    /**
+     * Areas of "focus" to inform the code mapper with. For example, cursor
+     * location, current selection, viewport, etc. Nested arrays denote
+     * priority: toplevel arrays are more important than inner arrays, and
+     * inner array priorities are based on items within that array. Items
+     * earlier in the arrays have higher priority.
+     */
+    focusLocations?: TextSpan[][];
+}
+
+export interface MapCodeRequest extends FileRequest {
+    command: CommandTypes.MapCode;
+    arguments: MapCodeRequestArgs;
+}
+
+export interface MapCodeResponse extends Response {
+    body: readonly FileCodeEdits[];
+}
+
 /**
  * Synchronous request for semantic diagnostics of one file.
  */

src/server/session.ts

@@ -1906,6 +1906,26 @@ export class Session<TMessage = string> implements EventSender {
         });
     }
 
+    private mapCode(args: protocol.MapCodeRequestArgs): protocol.FileCodeEdits[] {
+        const formatOptions = this.getHostFormatOptions();
+        const preferences = this.getHostPreferences();
+        const { file, languageService } = this.getFileAndLanguageServiceForSyntacticOperation(args);
+        const scriptInfo = this.projectService.getScriptInfoForNormalizedPath(file)!;
+        const focusLocations = args.mapping.focusLocations?.map(spans => {
+            return spans.map(loc => {
+                const start = scriptInfo.lineOffsetToPosition(loc.start.line, loc.start.offset);
+                const end = scriptInfo.lineOffsetToPosition(loc.end.line, loc.end.offset);
+                return {
+                    start,
+                    length: end - start,
+                };
+            });
+        });
+
+        const changes = languageService.mapCode(file, args.mapping.contents, focusLocations, formatOptions, preferences);
+        return this.mapTextChangesToCodeEdits(changes);
+    }
+
     private setCompilerOptionsForInferredProjects(args: protocol.SetCompilerOptionsForInferredProjectsArgs): void {
         this.projectService.setCompilerOptionsForInferredProjects(args.options, args.projectRootPath);
     }
@@ -3610,6 +3630,9 @@ export class Session<TMessage = string> implements EventSender {
         [protocol.CommandTypes.ProvideInlayHints]: (request: protocol.InlayHintsRequest) => {
             return this.requiredResponse(this.provideInlayHints(request.arguments));
         },
+        [protocol.CommandTypes.MapCode]: (request: protocol.MapCodeRequest) => {
+            return this.requiredResponse(this.mapCode(request.arguments));
+        },
     }));
 
     public addProtocolHandler(command: string, handler: (request: protocol.Request) => HandlerResponse) {

src/services/_namespaces/ts.MapCode.ts

@@ -0,0 +1,3 @@
+/* Generated file to emulate the ts.MapCode namespace. */
+
+export * from "../mapCode.js";

src/services/_namespaces/ts.ts

@@ -33,6 +33,8 @@ export { GoToDefinition };
 import * as InlayHints from "./ts.InlayHints.js";
 export { InlayHints };
 import * as JsDoc from "./ts.JsDoc.js";
+import * as MapCode from "./ts.MapCode.js";
+export { MapCode };
 export { JsDoc };
 import * as NavigateTo from "./ts.NavigateTo.js";
 export { NavigateTo };

src/services/mapCode.ts

@@ -0,0 +1,323 @@
+import {
+    Block,
+    ClassElement,
+    ClassLikeDeclaration,
+    createSourceFile,
+    FileTextChanges,
+    find,
+    findAncestor,
+    findLast,
+    flatten,
+    forEach,
+    formatting,
+    getTokenAtPosition,
+    isBlock,
+    isClassElement,
+    isClassLike,
+    isForInOrOfStatement,
+    isForStatement,
+    isIfStatement,
+    isInterfaceDeclaration,
+    isLabeledStatement,
+    isNamedDeclaration,
+    isSourceFile,
+    isTypeElement,
+    isWhileStatement,
+    LanguageServiceHost,
+    Mutable,
+    Node,
+    NodeArray,
+    or,
+    some,
+    SourceFile,
+    Statement,
+    SyntaxKind,
+    textChanges,
+    TextSpan,
+    TypeElement,
+    UserPreferences,
+} from "./_namespaces/ts.js";
+import { ChangeTracker } from "./textChanges.js";
+
+/** @internal */
+export function mapCode(
+    sourceFile: SourceFile,
+    contents: string[],
+    focusLocations: TextSpan[][] | undefined,
+    host: LanguageServiceHost,
+    formatContext: formatting.FormatContext,
+    preferences: UserPreferences,
+): FileTextChanges[] {
+    return textChanges.ChangeTracker.with(
+        { host, formatContext, preferences },
+        changeTracker => {
+            const parsed = contents.map(c => parse(sourceFile, c));
+            const flattenedLocations = focusLocations && flatten(focusLocations);
+            for (const nodes of parsed) {
+                placeNodeGroup(
+                    sourceFile,
+                    changeTracker,
+                    nodes,
+                    flattenedLocations,
+                );
+            }
+        },
+    );
+}
+
+/**
+ * Tries to parse something into either "top-level" statements, or into blocks
+ * of class-context definitions.
+ */
+function parse(sourceFile: SourceFile, content: string): NodeArray<Node> {
+    // We're going to speculatively parse different kinds of contexts to see
+    // which one makes the most sense, and grab the NodeArray from there. Do
+    // this as lazily as possible.
+    const nodeKinds = [
+        {
+            parse: () =>
+                createSourceFile(
+                    "__mapcode_content_nodes.ts",
+                    content,
+                    sourceFile.languageVersion,
+                    /*setParentNodes*/ true,
+                    sourceFile.scriptKind,
+                ),
+            body: (sf: SourceFile) => sf.statements,
+        },
+        {
+            parse: () =>
+                createSourceFile(
+                    "__mapcode_class_content_nodes.ts",
+                    `class __class {\n${content}\n}`,
+                    sourceFile.languageVersion,
+                    /*setParentNodes*/ true,
+                    sourceFile.scriptKind,
+                ),
+            body: (cw: SourceFile) => (cw.statements[0] as ClassLikeDeclaration).members,
+        },
+    ];
+
+    const parsedNodes = [];
+    for (const { parse, body } of nodeKinds) {
+        const sourceFile = parse();
+        const bod = body(sourceFile);
+        if (bod.length && sourceFile.parseDiagnostics.length === 0) {
+            // If we run into a case with no parse errors, this is likely the right kind.
+            return bod;
+        }
+        // We only want to keep the ones that have some kind of body.
+        else if (bod.length) {
+            // Otherwise, we'll need to look at others.
+            parsedNodes.push({ sourceFile, body: bod });
+        }
+    }
+    // Heuristic: fewer errors = more likely to be the right kind.
+    const { body } = parsedNodes.sort(
+        (a, b) =>
+            a.sourceFile.parseDiagnostics.length -
+            b.sourceFile.parseDiagnostics.length,
+    )[0];
+    return body;
+}
+
+function placeNodeGroup(
+    originalFile: SourceFile,
+    changeTracker: ChangeTracker,
+    changes: NodeArray<Node>,
+    focusLocations?: TextSpan[],
+) {
+    if (isClassElement(changes[0]) || isTypeElement(changes[0])) {
+        placeClassNodeGroup(
+            originalFile,
+            changeTracker,
+            changes as NodeArray<ClassElement>,
+            focusLocations,
+        );
+    }
+    else {
+        placeStatements(
+            originalFile,
+            changeTracker,
+            changes as NodeArray<Statement>,
+            focusLocations,
+        );
+    }
+}
+
+function placeClassNodeGroup(
+    originalFile: SourceFile,
+    changeTracker: ChangeTracker,
+    changes: NodeArray<ClassElement> | NodeArray<TypeElement>,
+    focusLocations?: TextSpan[],
+) {
+    let classOrInterface;
+    if (!focusLocations || !focusLocations.length) {
+        classOrInterface = find(originalFile.statements, or(isClassLike, isInterfaceDeclaration));
+    }
+    else {
+        classOrInterface = forEach(focusLocations, location =>
+            findAncestor(
+                getTokenAtPosition(originalFile, location.start),
+                or(isClassLike, isInterfaceDeclaration),
+            ));
+    }
+
+    if (!classOrInterface) {
+        // No class? don't insert.
+        return;
+    }
+
+    const firstMatch = classOrInterface.members.find(member => changes.some(change => matchNode(change, member)));
+    if (firstMatch) {
+        // can't be undefined here, since we know we have at least one match.
+        const lastMatch = findLast(
+            classOrInterface.members as NodeArray<ClassElement | TypeElement>,
+            member => changes.some(change => matchNode(change, member)),
+        )!;
+
+        forEach(changes, wipeNode);
+        changeTracker.replaceNodeRangeWithNodes(
+            originalFile,
+            firstMatch,
+            lastMatch,
+            changes,
+        );
+        return;
+    }
+
+    forEach(changes, wipeNode);
+    changeTracker.insertNodesAfter(
+        originalFile,
+        classOrInterface.members[classOrInterface.members.length - 1],
+        changes,
+    );
+}
+
+function placeStatements(
+    originalFile: SourceFile,
+    changeTracker: ChangeTracker,
+    changes: NodeArray<Statement>,
+    focusLocations?: TextSpan[],
+) {
+    if (!focusLocations?.length) {
+        changeTracker.insertNodesAtEndOfFile(
+            originalFile,
+            changes,
+            /*blankLineBetween*/ false,
+        );
+        return;
+    }
+
+    for (const location of focusLocations) {
+        const scope = findAncestor(
+            getTokenAtPosition(originalFile, location.start),
+            (block): block is Block | SourceFile =>
+                or(isBlock, isSourceFile)(block) &&
+                some(block.statements, origStmt => changes.some(newStmt => matchNode(newStmt, origStmt))),
+        );
+        if (scope) {
+            const start = scope.statements.find(stmt => changes.some(node => matchNode(node, stmt)));
+            if (start) {
+                // Can't be undefined here, since we know we have at least one match.
+                const end = findLast(scope.statements, stmt => changes.some(node => matchNode(node, stmt)))!;
+                forEach(changes, wipeNode);
+                changeTracker.replaceNodeRangeWithNodes(
+                    originalFile,
+                    start,
+                    end,
+                    changes,
+                );
+                return;
+            }
+        }
+    }
+
+    let scopeStatements: NodeArray<Statement> = originalFile.statements;
+    for (const location of focusLocations) {
+        const block = findAncestor(
+            getTokenAtPosition(originalFile, location.start),
+            isBlock,
+        );
+        if (block) {
+            scopeStatements = block.statements;
+            break;
+        }
+    }
+    forEach(changes, wipeNode);
+    changeTracker.insertNodesAfter(
+        originalFile,
+        scopeStatements[scopeStatements.length - 1],
+        changes,
+    );
+}
+
+function matchNode(a: Node, b: Node): boolean {
+    if (a.kind !== b.kind) {
+        return false;
+    }
+
+    if (a.kind === SyntaxKind.Constructor) {
+        return a.kind === b.kind;
+    }
+
+    if (isNamedDeclaration(a) && isNamedDeclaration(b)) {
+        return a.name.getText() === b.name.getText();
+    }
+
+    if (isIfStatement(a) && isIfStatement(b)) {
+        return (
+            a.expression.getText() === b.expression.getText()
+        );
+    }
+
+    if (isWhileStatement(a) && isWhileStatement(b)) {
+        return (
+            a.expression.getText() ===
+                b.expression.getText()
+        );
+    }
+
+    if (isForStatement(a) && isForStatement(b)) {
+        return (
+            a.initializer?.getText() ===
+                b.initializer?.getText() &&
+            a.incrementor?.getText() ===
+                b.incrementor?.getText() &&
+            a.condition?.getText() === b.condition?.getText()
+        );
+    }
+
+    if (isForInOrOfStatement(a) && isForInOrOfStatement(b)) {
+        return (
+            a.expression.getText() ===
+                b.expression.getText() &&
+            a.initializer.getText() ===
+                b.initializer.getText()
+        );
+    }
+
+    if (isLabeledStatement(a) && isLabeledStatement(b)) {
+        // If we're actually labeling/naming something, we should be a bit
+        // more lenient about when we match, so we don't care what the actual
+        // related statement is: we just replace.
+        return a.label.getText() === b.label.getText();
+    }
+
+    if (a.getText() === b.getText()) {
+        return true;
+    }
+
+    return false;
+}
+
+function wipeNode(node: Mutable<Node>) {
+    resetNodePositions(node);
+    node.parent = undefined!;
+}
+
+function resetNodePositions(node: Mutable<Node>) {
+    node.pos = -1;
+    node.end = -1;
+    node.forEachChild(resetNodePositions);
+}

src/services/services.ts

@@ -211,6 +211,7 @@ import {
     LinkedEditingInfo,
     LiteralType,
     map,
+    MapCode,
     mapDefined,
     MapLike,
     mapOneOrMany,
@@ -3165,6 +3166,17 @@ export function createLanguageService(
         return InlayHints.provideInlayHints(getInlayHintsContext(sourceFile, span, preferences));
     }
 
+    function mapCode(sourceFile: string, contents: string[], focusLocations: TextSpan[][] | undefined, formatOptions: FormatCodeSettings, preferences: UserPreferences): FileTextChanges[] {
+        return MapCode.mapCode(
+            syntaxTreeCache.getCurrentSourceFile(sourceFile),
+            contents,
+            focusLocations,
+            host,
+            formatting.getFormatContext(formatOptions, host),
+            preferences,
+        );
+    }
+
     const ls: LanguageService = {
         dispose,
         cleanupSemanticCache,
@@ -3236,6 +3248,7 @@ export function createLanguageService(
         provideInlayHints,
         getSupportedCodeFixes,
         getPasteEdits,
+        mapCode,
     };
 
     switch (languageServiceMode) {

src/services/types.ts

@@ -683,6 +683,8 @@ export interface LanguageService {
 
     getSupportedCodeFixes(fileName?: string): readonly string[];
 
+    /** @internal */ mapCode(fileName: string, contents: string[], focusLocations: TextSpan[][] | undefined, formatOptions: FormatCodeSettings, preferences: UserPreferences): readonly FileTextChanges[];
+
     dispose(): void;
     getPasteEdits(
         args: PasteEditsArgs,