Add history to REPL.

src/module/repl.wren

@@ -12,6 +12,9 @@ class Repl {
   construct new() {
     _cursor = 0
     _line = ""
+
+    _history = []
+    _historyIndex = 0
   }
 
   run() {
@@ -27,7 +30,7 @@ class Repl {
         return
       } else if (byte == Chars.ctrlD) {
         // If the line is empty, Ctrl_D exits.
-        if (_line == "") {
+        if (!_line.isEmpty) {
           System.print()
           return
         }
@@ -83,11 +86,9 @@ class Repl {
     if (escapeType == Chars.leftBracket) {
       // ESC [ sequence.
       if (value == EscapeBracket.up) {
-        // TODO: Handle this.
+        previousHistory()
-        System.print("up")
       } else if (value == EscapeBracket.down) {
-        // TODO: Handle this.
+        nextHistory()
-        System.print("down")
       } else if (value == EscapeBracket.left) {
         // Move the cursor left one.
         if (_cursor > 0) _cursor = _cursor - 1
@@ -101,22 +102,46 @@ class Repl {
     }
   }
 
+  previousHistory() {
+    if (_historyIndex == 0) return
+
+    _historyIndex = _historyIndex - 1
+    _line = _history[_historyIndex]
+    _cursor = _line.count
+  }
+
+  nextHistory() {
+    if (_historyIndex >= _history.count) return
+
+    _historyIndex = _historyIndex + 1
+    if (_historyIndex < _history.count) {
+      _line = _history[_historyIndex]
+      _cursor = _line.count
+    } else {
+      _line = ""
+      _cursor = 0
+    }
+  }
+
   executeInput() {
-    System.print()
+    // Add it to the history.
+    _history.add(_line)
+    _historyIndex = _history.count
+
+    // Reset the current line.
     var input = _line
     _line = ""
     _cursor = 0
 
+    System.print()
+
     // Guess if it looks like a statement or expression. Statements need to be
     // evaluated at the top level in case they declare variables, but they
     // don't return a value. Expressions need to have their result displayed.
     var tokens = lex(input, false)
-    if (tokens.isEmpty) {
+
-      // No code, so do nothing.
+    // No code, so do nothing.
-      // TODO: Temp.
+    if (tokens.isEmpty) return
-      System.print("empty")
-      return
-    }
 
     var first = tokens[0]
     var isStatement =
@@ -148,6 +173,7 @@ class Repl {
         // TODO: Handle error in result.toString.
         System.print("%(Color.brightWhite)%(result)%(Color.none)")
         return
+      }
     }
 
     System.print("%(Color.red)Runtime error: %(result)%(Color.none)")

src/module/repl.wren.inc

@@ -14,6 +14,9 @@ static const char* replModuleSource =
 "  construct new() {\n"
 "    _cursor = 0\n"
 "    _line = \"\"\n"
+"\n"
+"    _history = []\n"
+"    _historyIndex = 0\n"
 "  }\n"
 "\n"
 "  run() {\n"
@@ -29,7 +32,7 @@ static const char* replModuleSource =
 "        return\n"
 "      } else if (byte == Chars.ctrlD) {\n"
 "        // If the line is empty, Ctrl_D exits.\n"
-"        if (_line == \"\") {\n"
+"        if (!_line.isEmpty) {\n"
 "          System.print()\n"
 "          return\n"
 "        }\n"
@@ -85,11 +88,9 @@ static const char* replModuleSource =
 "    if (escapeType == Chars.leftBracket) {\n"
 "      // ESC [ sequence.\n"
 "      if (value == EscapeBracket.up) {\n"
-"        // TODO: Handle this.\n"
+"        previousHistory()\n"
-"        System.print(\"up\")\n"
 "      } else if (value == EscapeBracket.down) {\n"
-"        // TODO: Handle this.\n"
+"        nextHistory()\n"
-"        System.print(\"down\")\n"
 "      } else if (value == EscapeBracket.left) {\n"
 "        // Move the cursor left one.\n"
 "        if (_cursor > 0) _cursor = _cursor - 1\n"
@@ -103,22 +104,46 @@ static const char* replModuleSource =
 "    }\n"
 "  }\n"
 "\n"
+"  previousHistory() {\n"
+"    if (_historyIndex == 0) return\n"
+"\n"
+"    _historyIndex = _historyIndex - 1\n"
+"    _line = _history[_historyIndex]\n"
+"    _cursor = _line.count\n"
+"  }\n"
+"\n"
+"  nextHistory() {\n"
+"    if (_historyIndex >= _history.count) return\n"
+"\n"
+"    _historyIndex = _historyIndex + 1\n"
+"    if (_historyIndex < _history.count) {\n"
+"      _line = _history[_historyIndex]\n"
+"      _cursor = _line.count\n"
+"    } else {\n"
+"      _line = \"\"\n"
+"      _cursor = 0\n"
+"    }\n"
+"  }\n"
+"\n"
 "  executeInput() {\n"
-"    System.print()\n"
+"    // Add it to the history.\n"
+"    _history.add(_line)\n"
+"    _historyIndex = _history.count\n"
+"\n"
+"    // Reset the current line.\n"
 "    var input = _line\n"
 "    _line = \"\"\n"
 "    _cursor = 0\n"
 "\n"
+"    System.print()\n"
+"\n"
 "    // Guess if it looks like a statement or expression. Statements need to be\n"
 "    // evaluated at the top level in case they declare variables, but they\n"
 "    // don't return a value. Expressions need to have their result displayed.\n"
 "    var tokens = lex(input, false)\n"
-"    if (tokens.isEmpty) {\n"
+"\n"
-"      // No code, so do nothing.\n"
+"    // No code, so do nothing.\n"
-"      // TODO: Temp.\n"
+"    if (tokens.isEmpty) return\n"
-"      System.print(\"empty\")\n"
-"      return\n"
-"    }\n"
 "\n"
 "    var first = tokens[0]\n"
 "    var isStatement =\n"
@@ -132,30 +157,29 @@ static const char* replModuleSource =
 "        first.type == Token.varKeyword ||\n"
 "        first.type == Token.whileKeyword\n"
 "\n"
+"    var fiber\n"
 "    if (isStatement) {\n"
-"      var fiber = Fiber.new {\n"
+"      fiber = Fiber.new {\n"
 "        Meta.eval(input)\n"
 "      }\n"
 "\n"
 "      var result = fiber.try()\n"
-"      if (fiber.error != null) {\n"
+"      if (fiber.error == null) return\n"
-"        System.print(\"%(Color.red)Runtime error: %(result)%(Color.none)\")\n"
-"        // TODO: Print entire stack.\n"
-"      }\n"
 "    } else {\n"
 "      var function = Meta.compileExpression(input)\n"
 "      if (function == null) return\n"
 "\n"
-"      var fiber = Fiber.new(function)\n"
+"      fiber = Fiber.new(function)\n"
 "      var result = fiber.try()\n"
 "      if (fiber.error == null) {\n"
 "        // TODO: Handle error in result.toString.\n"
 "        System.print(\"%(Color.brightWhite)%(result)%(Color.none)\")\n"
-"      } else {\n"
+"        return\n"
-"        System.print(\"%(Color.red)Runtime error: %(result)%(Color.none)\")\n"
-"        // TODO: Print entire stack.\n"
 "      }\n"
 "    }\n"
+"\n"
+"    System.print(\"%(Color.red)Runtime error: %(result)%(Color.none)\")\n"
+"    // TODO: Print entire stack.\n"
 "  }\n"
 "\n"
 "  lex(line, includeWhitespace) {\n"