add support for custom variables (#1921)

* add support for custom variables

* support for string[] variables

* rename "variables" to "env"

Author: bobbrow

Extension/c_cpp_properties.schema.json

@@ -107,6 +107,26 @@
                 }
             }
         },
+        "env": {
+            "type": "object",
+            "description": "Custom variables that can be resused anywhere in this file using the ${variable} or ${env:variable} syntax.",
+            "patternProperties": {
+                "(?!^workspaceFolder$)(?!^workspaceRoot$)(?!^default$)(^.+$)": {
+                    "oneOf": [
+                        {
+                            "type": "string"
+                        },
+                        {
+                            "type": "array",
+                            "items": {
+                                "type": "string"
+                            }
+                        }
+                    ]
+                }
+            },
+            "additionalProperties": false
+        },
         "version": {
             "type": "integer",
             "description": "Version of the configuration file. This property is managed by the extension. Please do not change it."
@@ -116,6 +136,9 @@
         "configurations": {
             "$ref": "#/definitions/configurations"
         },
+        "env": {
+            "$ref": "#/definitions/env"
+        },
         "version": {
             "$ref": "#/definitions/version"
         }

Extension/src/LanguageServer/configurations.ts

@@ -34,6 +34,7 @@ function getDefaultCppProperties(): ConfigurationJson {
 
 interface ConfigurationJson {
     configurations: Configuration[];
+    env?: {[key: string]: string | string[]};
     version: number;
 }
 
@@ -336,7 +337,11 @@ export class CppProperties {
         let result: string[] = [];
         entries.forEach(entry => {
             if (entry === "${default}") {
-                result = result.concat(defaultValue);
+                // package.json default values for string[] properties is null.
+                // If no default is set, return an empty array instead of an array with `null` in it.
+                if (defaultValue !== null) {
+                    result = result.concat(defaultValue);
+                }
             } else {
                 result.push(entry);
             }
@@ -348,7 +353,7 @@ export class CppProperties {
         let result: string[] = [];
         if (paths) {
             paths.forEach(entry => {
-                let entries: string[] = util.resolveVariables(entry).split(";").filter(e => e);
+                let entries: string[] = util.resolveVariables(entry, this.configurationJson.env).split(";").filter(e => e);
                 entries = this.resolveDefaults(entries, defaultValue);
                 result = result.concat(entries);
             });
@@ -363,7 +368,7 @@ export class CppProperties {
         if (typeof input === "boolean") {
             return input;
         }
-        return util.resolveVariables(input);
+        return util.resolveVariables(input, this.configurationJson.env);
     }
 
     private updateConfiguration(property: string[], defaultValue: string[]): string[];
@@ -524,6 +529,13 @@ export class CppProperties {
                 this.currentConfigurationIndex.Value = this.getConfigIndexForPlatform(newJson);
             }
 
+            // Remove disallowed variable overrides
+            if (this.configurationJson.env) {
+                delete this.configurationJson.env['workspaceRoot'];
+                delete this.configurationJson.env['workspaceFolder'];
+                delete this.configurationJson.env['default'];
+            }
+
             // Warning: There is a chance that this is incorrect in the event that the c_cpp_properties.json file was created before
             // the system includes were available.
             this.configurationIncomplete = false;

Extension/src/common.ts

@@ -143,10 +143,13 @@ export function showReleaseNotes(): void {
     vscode.commands.executeCommand('vscode.previewHtml', vscode.Uri.file(getExtensionFilePath("ReleaseNotes.html")), vscode.ViewColumn.One, "C/C++ Extension Release Notes");
 }
 
-export function resolveVariables(input: string): string {
+export function resolveVariables(input: string, additionalEnvironment: {[key: string]: string | string[]}): string {
     if (!input) {
         return "";
     }
+    if (!additionalEnvironment) {
+        additionalEnvironment = {};
+    }
 
     // Replace environment and configuration variables.
     let regexp: RegExp = /\$\{((env|config)(.|:))?(.*?)\}/g;
@@ -158,7 +161,18 @@ export function resolveVariables(input: string): string {
         }
         let newValue: string = undefined;
         switch (varType) {
-            case "env": { newValue = process.env[name]; break; }
+            case "env": {
+                let v: string | string[] = additionalEnvironment[name];
+                if (typeof v === "string") {
+                    newValue = v;
+                } else if (input === match && v instanceof Array) {
+                    newValue = v.join(";");
+                }
+                if (!newValue) {
+                    newValue = process.env[name];
+                }
+                break;
+            }
             case "config": {
                 let config: vscode.WorkspaceConfiguration = vscode.workspace.getConfiguration();
                 let keys: string[] = name.split('.');