JavaScript editor: add autocompletion for ', ", `, (, [, and {

MongoView/Synax Highlighting/JavaScriptHighlighter.swift

@@ -26,6 +26,7 @@ class JavaScriptHighlighter {
     private var attributed: NSMutableAttributedString
     private var currentIndex: String.Index!
     private var indent = ""
+    private(set) var tokens = [(token: TokenType, range: NSRange)]()
     
     init(text: String) {
         self.text = text
@@ -94,6 +95,7 @@ class JavaScriptHighlighter {
             return
         }
         attributed.addAttribute(.foregroundColor, value: color, range: range)
+        tokens.append((token, range))
     }
 
     private func consumeExpression() {
@@ -173,32 +175,42 @@ class JavaScriptHighlighter {
     
     private func consumeTemplateString() {
         var stringFragmentStart: String.Index? = currentIndex
+        
+        func emitTemplateStringFragment() {
+            guard stringFragmentStart != currentIndex else { return }
+            print("Template string fragment: '\(text[stringFragmentStart!..<currentIndex])'")
+            emit(token: .string, range: range(from: stringFragmentStart!, to: currentIndex))
+            stringFragmentStart = currentIndex
+        }
+        
         consume() // opening `
+        
         while currentIndex < text.endIndex {
-            if peek(length: 2) == "${" {
+            if peek() == "$" {
+                emitTemplateStringFragment()
                 consume() // $
-                consume() // {
-                print("Template string fragment: '\(text[stringFragmentStart!..<currentIndex])'")
-                emit(token: .string, range: range(from: stringFragmentStart!, to: currentIndex))
-                consumeTemplateStringExpression()
-                stringFragmentStart = currentIndex
-                if currentIndex < text.endIndex && peek() == "}" {
-                    consume()
+                if peek() == "{" {
+                    consume() // {
+                    emitTemplateStringFragment()
+                    consumeTemplateStringExpression()
+                    stringFragmentStart = currentIndex
+                    if currentIndex < text.endIndex && peek() == "}" {
+                        consume() // }
+                    }
+
                 }
             } else if peek() == "`" {
                 stringFragmentStart = stringFragmentStart ?? currentIndex
                 consume() // `
-                print("Template string fragment: '\(text[stringFragmentStart!..<currentIndex])'")
-                emit(token: .string, range: range(from: stringFragmentStart!, to: currentIndex))
+                emitTemplateStringFragment()
                 stringFragmentStart = nil
                 break
             } else {
                 consume()
             }
         }
-        if let start = stringFragmentStart {
-            print("Template string fragment: '\(text[start..<currentIndex])'")
-            emit(token: .string, range: range(from: start, to: currentIndex))
+        if stringFragmentStart != nil {
+            emitTemplateStringFragment()
         }
     }
     

MongoView/Views/JavaScriptEditorView.swift

@@ -10,6 +10,8 @@ import AppKit
 
 class JavaScriptEditorView: NSTextView {
     
+    var highlighter: JavaScriptHighlighter?
+    
     override var string: String {
         didSet {
             rehighlight()
@@ -17,7 +19,23 @@ class JavaScriptEditorView: NSTextView {
     }
 
     func rehighlight() {
-        JavaScriptHighlighter(mutableAttributed: self.textStorage!).highlight()
+        highlighter = JavaScriptHighlighter(mutableAttributed: self.textStorage!)
+        highlighter!.highlight()
+    }
+    
+    override func shouldChangeText(in affectedCharRange: NSRange, replacementString: String?) -> Bool {
+        guard super.shouldChangeText(in: affectedCharRange, replacementString: replacementString) else {
+            return false
+        }
+        
+        if affectedCharRange.length == 0,
+            let string = replacementString,
+            string.count == 1,
+            tryAutocompleteCharacter(for: affectedCharRange, string: string) {
+            return false
+        }
+
+        return true
     }
 
     override func didChangeText() {
@@ -25,4 +43,43 @@ class JavaScriptEditorView: NSTextView {
         
         super.didChangeText()
     }
+    
+    func tryAutocompleteCharacter(for range: NSRange, string inserted: String) -> Bool {
+        if let end = autocompleteResultFor(string: inserted, in: range) {
+            textStorage!.insert(NSAttributedString(string: "\(inserted)\(end)"), at: range.location)
+            didChangeText()
+            setSelectedRange(NSRange(location: range.location + 1, length: 0))
+            return true
+        } else {
+            return false
+        }
+    }
+    
+    private func autocompleteResultFor(string: String, in range: NSRange) -> String? {
+        switch string {
+        case "'", "\"", "`":
+            return token(at: range.location) != .string ? string : nil
+        case "(":
+            return token(at: range.location) != .string ? ")" : nil
+        case "[":
+            return token(at: range.location) != .string ? "]" : nil
+        case "{":
+            var prevChar: Unicode.Scalar?
+            if range.location > 0 {
+                let index = self.string.index(self.string.startIndex, offsetBy: range.location - 1)
+                prevChar = self.string.unicodeScalars[index]
+            }
+            return token(at: range.location) != .string || (prevChar == "$") ? "}" : nil
+        default:
+            return nil
+        }
+    }
+
+    private func token(at index: Int) -> JavaScriptHighlighter.TokenType? {
+        guard let highlighter = highlighter else { return nil }
+        for (token, range) in highlighter.tokens where range.contains(index) {
+            return token
+        }
+        return nil
+    }
 }

jstest/main.swift

@@ -8,6 +8,6 @@
 
 import Foundation
 
-let source = "a ? 'foo' : b ? 'bar' : 'baz'"
+let source = "`$foo ${blah} bar`"
 _ = JavaScriptHighlighter(text: source).highlight()