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(PowerShellGH-1336) Add syntax aware folding provider
Previously the Powershell extension used the default VSCode indentation based folding regions. This commit adds the skeleton for a syntax aware, client-side folding provider as per the API introduced in VSCode 1.23.0 * The client side detection uses the PowerShell Textmate grammar file and the vscode-text node module to parse the text file into tokens which will be matched in later commits. * However due to the way vscode imports the vscode-textmate module we can't simply just import it, instead we need to use file based require statements microsoft/vscode#46281 * This also means it's difficult to use any typings exposed in that module. As we only need one interface, this is replicated verbatim in the file, but not exported * Logging is added to help diagnose potential issues
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‎package.json

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@@ -5,7 +5,7 @@
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"publisher": "ms-vscode",
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"description": "Develop PowerShell scripts in Visual Studio Code!",
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"engines": {
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"vscode": "^1.22.0"
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"vscode": "^1.23.0"
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},
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"license": "SEE LICENSE IN LICENSE.txt",
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"homepage": "https://github.com/PowerShell/vscode-powershell/blob/master/README.md",

‎src/features/Folding.ts

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import * as path from "path";
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import * as vscode from "vscode";
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import {
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DocumentSelector,
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LanguageClient,
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} from "vscode-languageclient";
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import { IFeature } from "../feature";
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import { Logger } from "../logging";
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/**
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* Defines a grammar file that is in a VS Code Extension
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*/
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interface IExtensionGrammar {
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/**
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* The name of the language, e.g. powershell
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*/
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language?: string;
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/**
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* The absolute path to the grammar file
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*/
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path?: string;
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/**
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* The path to the extension
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*/
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extensionPath?: string;
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}
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/**
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* Defines a VS Code extension with minimal properities for grammar contribution
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*/
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interface IExtensionPackage {
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/**
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* Hashtable of items this extension contributes
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*/
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contributes?: {
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/**
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* Array of grammars this extension supports
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*/
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grammars?: IExtensionGrammar[],
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};
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}
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/**
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* Defines a grammar token in a text document
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* Need to reproduce the IToken interface from vscode-textmate due to the odd way it has to be required
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* https://github.com/Microsoft/vscode-textmate/blob/46af9487e1c8fa78aa1f2e2/release/main.d.ts#L161-L165
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*/
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interface IToken {
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/**
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* Zero based offset where the token starts
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*/
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startIndex: number;
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/**
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* Zero based offset where the token ends
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*/
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readonly endIndex: number;
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/**
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* Array of scope names that the token is a member of
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*/
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readonly scopes: string[];
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}
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/**
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* Defines a list of grammar tokens, typically for an entire text document
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*/
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interface ITokenList extends Array<IToken> { }
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/**
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* Due to how the vscode-textmate library is required, we need to minimally define a Grammar object, which
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* can be used to tokenize a text document.
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* https://github.com/Microsoft/vscode-textmate/blob/46af9487e1c8fa78aa1f2e2/release/main.d.ts#L92-L108
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*/
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interface IGrammar {
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/**
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* Tokenize `lineText` using previous line state `prevState`.
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*/
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tokenizeLine(lineText: any, prevState: any): any;
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}
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/**
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* Defines a pair line numbers which describes a potential folding range in a text document
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*/
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class LineNumberRange {
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/**
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* The zero-based line number of the start of the range
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*/
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public startline: number;
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/**
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* The zero-based line number of the end of the range
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*/
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public endline: number;
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/**
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* The type of range this represents
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*/
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public rangeKind: vscode.FoldingRangeKind;
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constructor(
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rangeKind: vscode.FoldingRangeKind,
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) {
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this.rangeKind = rangeKind;
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}
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/**
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* Build the range based on a pair of grammar tokens
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* @param start The token where the range starts
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* @param end The token where the range ends
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* @param document The text document
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* @returns Built LineNumberRange object
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*/
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public fromTokenPair(
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start: IToken,
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end: IToken,
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document: vscode.TextDocument,
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): LineNumberRange {
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this.startline = document.positionAt(start.startIndex).line;
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this.endline = document.positionAt(end.startIndex).line;
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return this;
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}
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/**
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* Build the range based on a pair of line numbers
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* @param startLine The line where the range starts
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* @param endLine The line where the range ends
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* @returns Built LineNumberRange object
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*/
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public fromLinePair(
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startLine: number,
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endLine: number,
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): LineNumberRange {
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this.startline = startLine;
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this.endline = endLine;
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return this;
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}
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/**
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* Whether this line number range, is a valid folding range in the document
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* @returns Whether the range passes all validation checks
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*/
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public isValidRange(): boolean {
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// Start and end lines must be defined and positive integers
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if (this.startline == null || this.endline == null) { return false; }
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if (this.startline < 0 || this.endline < 0) { return false; }
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// End line number cannot be before the start
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if (this.startline > this.endline) { return false; }
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// Folding ranges must span at least 2 lines
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return (this.endline - this.startline >= 1);
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}
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/**
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* Creates a vscode.FoldingRange object based on this object
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* @returns A Folding Range object for use with the Folding Provider
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*/
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public toFoldingRange(): vscode.FoldingRange {
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return new vscode.FoldingRange(this.startline, this.endline, this.rangeKind);
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}
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}
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/**
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* An array of line number ranges
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*/
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interface ILineNumberRangeList extends Array<LineNumberRange> { }
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/**
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* A PowerShell syntax aware Folding Provider
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*/
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export class FoldingProvider implements vscode.FoldingRangeProvider {
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private powershellGrammar: IGrammar;
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constructor(
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powershellGrammar: IGrammar,
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) {
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this.powershellGrammar = powershellGrammar;
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}
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/**
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* Given a text document, parse the document and return a list of code folding ranges.
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* @param document Text document to parse
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* @param context Not used
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* @param token Not used
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*/
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public async provideFoldingRanges(
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document: vscode.TextDocument,
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context: vscode.FoldingContext,
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token: vscode.CancellationToken,
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): Promise<vscode.FoldingRange[]> {
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// If the grammar hasn't been setup correctly, return empty result
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if (this.powershellGrammar == null) { return []; }
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// Convert the document text into a series of grammar tokens
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const tokens: ITokenList = this.powershellGrammar.tokenizeLine(document.getText(), null).tokens;
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// Parse the token list looking for matching tokens and return
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// a list of LineNumberRange objects. Then filter the list and only return matches
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// that are a valid folding range e.g. It meets a minimum line span limit
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const foldableRegions = this.extractFoldableRegions(tokens, document)
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.filter((item) => item.isValidRange());
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// Sort the list of matched tokens, starting at the top of the document,
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// and ensure that, in the case of multiple ranges starting the same line,
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// that the largest range (i.e. most number of lines spanned) is sorted
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// first. This is needed as vscode will just ignore any duplicate folding
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// ranges.
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foldableRegions.sort((a: LineNumberRange, b: LineNumberRange) => {
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// Initially look at the start line
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if (a.startline > b.startline) { return 1; }
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if (a.startline < b.startline) { return -1; }
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// They have the same start line so now consider the end line.
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// The biggest line range is sorted first
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if (a.endline > b.endline) { return -1; }
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if (a.endline < b.endline) { return 1; }
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// They're the same
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return 0;
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});
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// Convert the matched token list into a FoldingRange[]
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const foldingRanges = [];
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foldableRegions.forEach((item) => { foldingRanges.push(item.toFoldingRange()); });
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return foldingRanges;
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}
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/**
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* Given a list of tokens, return a list of line number ranges which could be folding regions in the document
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* @param tokens List of grammar tokens to parse
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* @param document The source text document
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* @returns A list of LineNumberRange objects of the possible document folding regions
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*/
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private extractFoldableRegions(
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tokens: ITokenList,
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document: vscode.TextDocument,
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): ILineNumberRangeList {
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const matchedTokens: ILineNumberRangeList = [];
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return matchedTokens;
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}
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}
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export class FoldingFeature implements IFeature {
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private foldingProvider: FoldingProvider;
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/**
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* Constructs a handler for the FoldingProvider. It returns success if the required grammar file can not be located
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* but does not regist a provider. This causes VS Code to instead still use the indentation based provider
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* @param logger The logging object to send messages to
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* @param documentSelector documentSelector object for this Folding Provider
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*/
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constructor(private logger: Logger, documentSelector: DocumentSelector) {
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const grammar: IGrammar = this.grammar(logger);
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// If the PowerShell grammar is not available for some reason, don't register a folding provider,
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// which reverts VSCode to the default indentation style folding
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if (grammar == null) {
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logger.writeWarning("Unable to load the PowerShell grammar file");
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return;
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}
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this.foldingProvider = new FoldingProvider(grammar);
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vscode.languages.registerFoldingRangeProvider(documentSelector, this.foldingProvider);
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logger.write("Syntax Folding Provider registered");
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}
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/* dispose() is required by the IFeature interface, but is not required by this feature */
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public dispose(): any { return undefined; }
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/* setLanguageClient() is required by the IFeature interface, but is not required by this feature */
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public setLanguageClient(languageclient: LanguageClient): void { return undefined; }
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/**
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* Returns the PowerShell grammar parser, from the vscode-textmate node module
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* @param logger The logging object to send messages to
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* @returns A grammar parser for the PowerShell language is succesful or undefined if an error occured
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*/
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public grammar(logger: Logger): IGrammar {
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const tm = this.getCoreNodeModule("vscode-textmate", logger);
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if (tm == null) { return undefined; }
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logger.writeDiagnostic(`Loaded the vscode-textmate module`);
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const registry = new tm.Registry();
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if (registry == null) { return undefined; }
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logger.writeDiagnostic(`Created the textmate Registry`);
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const grammarPath = this.powerShellGrammarPath();
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if (grammarPath == null) { return undefined; }
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logger.writeDiagnostic(`PowerShell grammar file specified as ${grammarPath}`);
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try {
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return registry.loadGrammarFromPathSync(grammarPath);
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} catch (err) {
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logger.writeError(`Error while loading the PowerShell grammar file at ${grammarPath}`, err);
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}
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}
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/**
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* Returns a node module installed within VSCode, or null if it fails.
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* Some node modules (e.g. vscode-textmate) cannot be required directly, instead the known module locations
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* must be tried. Documented in https://github.com/Microsoft/vscode/issues/46281
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* @param moduleName Name of the module to load e.g. vscode-textmate
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* @param logger The logging object to send messages to
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* @returns The required module, or null if the module cannot be required
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*/
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private getCoreNodeModule(moduleName: string, logger: Logger) {
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// Attempt to load the module from known locations
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const loadLocations: string[] = [
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`${vscode.env.appRoot}/node_modules.asar/${moduleName}`,
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`${vscode.env.appRoot}/node_modules/${moduleName}`,
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];
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for (const filename of loadLocations) {
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try {
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const mod = require(filename);
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logger.writeDiagnostic(`Succesfully required ${filename}`);
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return mod;
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} catch (err) {
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logger.writeError(`Error while attempting to require ${filename}`, err);
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}
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}
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return null;
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}
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/**
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* Search all of the loaded extenions for the PowerShell grammar file
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* @returns The absolute path to the PowerShell grammar file. Returns undefined if the path cannot be located.
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*/
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private powerShellGrammarPath(): string {
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// Go through all the extension packages and search for PowerShell grammars,
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// returning the path to the first we find
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for (const ext of vscode.extensions.all) {
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if (!(ext.packageJSON && ext.packageJSON.contributes && ext.packageJSON.contributes.grammars)) {
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continue;
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}
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for (const grammar of ext.packageJSON.contributes.grammars) {
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if (grammar.language !== "powershell") { continue; }
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return path.join(ext.extensionPath, grammar.path);
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}
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}
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return undefined;
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}
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}

‎src/main.ts

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import { ExamplesFeature } from "./features/Examples";
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import { ExpandAliasFeature } from "./features/ExpandAlias";
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import { ExtensionCommandsFeature } from "./features/ExtensionCommands";
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import { FoldingFeature } from "./features/Folding";
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import { GenerateBugReportFeature } from "./features/GenerateBugReport";
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import { HelpCompletionFeature } from "./features/HelpCompletion";
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import { NewFileOrProjectFeature } from "./features/NewFileOrProject";
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new SpecifyScriptArgsFeature(context),
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new HelpCompletionFeature(logger),
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new CustomViewsFeature(),
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new FoldingFeature(logger, documentSelector),
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];
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sessionManager.setExtensionFeatures(extensionFeatures);

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