Add indentation for Scheme

Just copied over the Clojure indentation rules to Scheme and changed
the keywords to suit the language, so that Scheme programs can be
automatically indented too

lib/ace/mode/scheme.js

@@ -39,15 +39,92 @@ define(function(require, exports, module) {
 var oop = require("../lib/oop");
 var TextMode = require("./text").Mode;
 var SchemeHighlightRules = require("./scheme_highlight_rules").SchemeHighlightRules;
+var MatchingParensOutdent = require("./matching_parens_outdent").MatchingParensOutdent;
 
 var Mode = function() {
     this.HighlightRules = SchemeHighlightRules;
+	this.$outdent = new MatchingParensOutdent();
 };
 oop.inherits(Mode, TextMode);
 
 (function() {
        
     this.lineCommentStart = ";";
+    this.minorIndentFunctions = ["define", "lambda", "define-macro", "define-syntax", "syntax-rules", "define-record-type", "define-structure"];
+
+    this.$toIndent = function(str) {
+        return str.split('').map(function(ch) {
+            if (/\s/.exec(ch)) {
+                return ch;
+            } else {
+                return ' ';
+            }
+        }).join('');
+    };
+
+    this.$calculateIndent = function(line, tab) {
+        var baseIndent = this.$getIndent(line);
+        var delta = 0;
+        var isParen, ch;
+        // Walk back from end of line, find matching braces
+        for (var i = line.length - 1; i >= 0; i--) {
+            ch = line[i];
+            if (ch === '(') {
+                delta--;
+                isParen = true;
+            } else if (ch === '(' || ch === '[' || ch === '{') {
+                delta--;
+                isParen = false;
+            } else if (ch === ')' || ch === ']' || ch === '}') {
+                delta++;
+            }
+            if (delta < 0) {
+                break;
+            }
+        }
+        if (delta < 0 && isParen) {
+            // Were more brackets opened than closed and was a ( left open?
+            i += 1;
+            var iBefore = i;
+            var fn = '';
+            while (true) {
+                ch = line[i];
+                if (ch === ' ' || ch === '\t') {
+                    if(this.minorIndentFunctions.indexOf(fn) !== -1) {
+                        return this.$toIndent(line.substring(0, iBefore - 1) + tab);
+                    } else {
+                        return this.$toIndent(line.substring(0, i + 1));
+                    }
+                } else if (ch === undefined) {
+                    return this.$toIndent(line.substring(0, iBefore - 1) + tab);
+                }
+                fn += line[i];
+                i++;
+            }
+        } else if(delta < 0 && !isParen) {
+            // Were more brackets openend than closed and was it not a (?
+            return this.$toIndent(line.substring(0, i+1));
+        } else if(delta > 0) {
+            // Mere more brackets closed than opened? Outdent.
+            baseIndent = baseIndent.substring(0, baseIndent.length - tab.length);
+            return baseIndent;
+        } else {
+            // Were they nicely matched? Just indent like line before.
+            return baseIndent;
+        }
+    };
+
+    this.getNextLineIndent = function(state, line, tab) {
+        return this.$calculateIndent(line, tab);
+    };
+
+    this.checkOutdent = function(state, line, input) {
+        return this.$outdent.checkOutdent(line, input);
+    };
+
+    this.autoOutdent = function(state, doc, row) {
+        this.$outdent.autoOutdent(doc, row);
+    };
     
     this.$id = "ace/mode/scheme";
 }).call(Mode.prototype);