From 3757643e2977f34382f6e334cb4c8b6a77944e98 Mon Sep 17 00:00:00 2001
From: Colin Holzman <colin.holzman@protonmail.com>
Date: Mon, 21 Sep 2020 11:30:00 -0400
Subject: [PATCH] add a command to replace selected text with it's math.js
 evaluation

---
 package.json     |  8 ++++++++
 src/decorator.ts | 25 +++++++++++++++++++++++++
 src/document.ts  |  7 ++++---
 src/extension.ts |  3 +++
 4 files changed, 40 insertions(+), 3 deletions(-)

diff --git a/package.json b/package.json
index 969c6b5..8540ec0 100644
--- a/package.json
+++ b/package.json
@@ -32,6 +32,14 @@
         "onLanguage:markdown"
     ],
     "main": "./out/extension.js",
+    "contributes": {
+        "commands": [
+            {
+                "command": "Mathpad.replace",
+                "title": "Mathpad: Replace"
+            }
+        ]
+    },
     "scripts": {
         "vscode:prepublish": "npm run compile",
         "compile": "tsc -p ./",
diff --git a/src/decorator.ts b/src/decorator.ts
index 40fcef5..fe40826 100644
--- a/src/decorator.ts
+++ b/src/decorator.ts
@@ -11,6 +11,7 @@ import {
     window,
     workspace,
     ExtensionContext,
+    Range
 } from "vscode";
 import MathDocument from "./document";
 import { MathJsStatic } from 'mathjs';
@@ -80,6 +81,30 @@ export default class EditorDecorator implements Disposable {
         window.visibleTextEditors.forEach(editor => this.renderEditor(editor));
     }
 
+    renderSelection() {
+        window.visibleTextEditors.forEach(editor => {
+            editor.selections.forEach(selection => {
+                editor.edit(editBuilder => {
+                    const range = new Range(selection.start, selection.end);
+                    const text = editor.document.getText(range);
+                    const scope = this.getMathDocument(editor.document).scope;
+                    let evaluated = '';
+                    try {
+                        evaluated = this.math.evaluate(text, scope);
+                        if (evaluated === undefined) {
+                            evaluated = '';
+                        }
+                        evaluated = evaluated.toString();
+                    } catch (e) {
+                        evaluated = e.toString();
+                    }
+                    editBuilder.replace(selection, evaluated);
+                });
+            });
+        });
+        this.renderAll();
+    }
+
     /**
      * Re-render all math decorations on the given editor.
      */
diff --git a/src/document.ts b/src/document.ts
index 8b5986e..d8ee91c 100644
--- a/src/document.ts
+++ b/src/document.ts
@@ -8,6 +8,7 @@ import { defaultScope } from './math';
 export default class MathDocument {
     document: TextDocument;
     results = new Map<number, any>();
+    scope: any
 
     // Expression compiler cache.
     private compileCache = new Map<string, math.EvalFunction>();
@@ -21,7 +22,7 @@ export default class MathDocument {
      */
     evaluate() {
         this.results.clear();
-        let scope = defaultScope();
+        this.scope = defaultScope();
 
         for (let lineNumber = 0; lineNumber < this.document.lineCount; lineNumber++) {
             const line = this.document.lineAt(lineNumber);
@@ -32,8 +33,8 @@ export default class MathDocument {
 
                 if (compiled) {
                     try {
-                        const result = compiled.evaluate(scope);
-                        scope["last"] = result;
+                        const result = compiled.evaluate(this.scope);
+                        this.scope["last"] = result;
 
                         // Only display value results.
                         if (typeof result !== "function" && typeof result !== "undefined") {
diff --git a/src/extension.ts b/src/extension.ts
index fa498c9..79a1431 100644
--- a/src/extension.ts
+++ b/src/extension.ts
@@ -4,4 +4,7 @@ import EditorDecorator from './decorator';
 export function activate(context: vscode.ExtensionContext) {
     let decorator = new EditorDecorator(context);
     context.subscriptions.push(decorator);
+    context.subscriptions.push(vscode.commands.registerCommand('Mathpad.replace', () => {
+        decorator.renderSelection();
+    }));
 }