Added safe soaking on non-existent variables.

lib/nodes.js

@@ -425,34 +425,46 @@
     ValueNode.prototype.is_statement = function is_statement() {
       return this.base.is_statement && this.base.is_statement() && !this.has_properties();
     };
+    // Works out if the value is the start of a chain.
+    ValueNode.prototype.is_start = function is_start(o) {
+      var node;
+      if (this === o.chain_root && this.properties[0] instanceof AccessorNode) {
+        return true;
+      }
+      node = o.chain_root.base || o.chain_root.variable;
+      while (node instanceof CallNode) {
+        node = node.variable;
+      }
+      return node === this;
+    };
     // We compile a value to JavaScript by compiling and joining each property.
     // Things get much more insteresting if the chain of properties has *soak*
     // operators `?.` interspersed. Then we have to take care not to accidentally
     // evaluate a anything twice when building the soak chain.
     ValueNode.prototype.compile_node = function compile_node(o) {
-      var _b, _c, _d, baseline, complete, only, op, part, prop, props, temp;
+      var _b, _c, baseline, complete, i, only, op, part, prop, props, temp;
       only = del(o, 'only_first');
       op = del(o, 'operation');
       props = only ? this.properties.slice(0, this.properties.length - 1) : this.properties;
-      if (!(o.chain_root)) {
+      o.chain_root = o.chain_root || this;
-        o.chain_root = this;
-      }
       baseline = this.base.compile(o);
       if (this.base instanceof ObjectNode && this.has_properties()) {
         baseline = ("(" + baseline + ")");
       }
       complete = (this.last = baseline);
-      _c = props;
+      _b = props;
-      for (_b = 0, _d = _c.length; _b < _d; _b++) {
+      for (i = 0, _c = _b.length; i < _c; i++) {
-        prop = _c[_b];
+        prop = _b[i];
         this.source = baseline;
         if (prop.soak_node) {
-          if (this.base instanceof CallNode && prop === props[0]) {
+          if (this.base instanceof CallNode && i === 0) {
             temp = o.scope.free_variable();
-            complete = ("(" + temp + " = " + complete + ")" + this.SOAK) + (baseline = temp + prop.compile(o));
+            complete = ("(" + (baseline = temp) + " = (" + complete + "))");
-          } else {
-            complete = complete + this.SOAK + (baseline += prop.compile(o));
           }
+          if (i === 0 && this.is_start(o)) {
+            complete = ("typeof " + complete + " === \"undefined\" || " + baseline);
+          }
+          complete += this.SOAK + (baseline += prop.compile(o));
         } else {
           part = prop.compile(o);
           baseline += part;

src/nodes.coffee

@@ -298,6 +298,13 @@ exports.ValueNode: class ValueNode extends BaseNode
   # Values are considered to be statements if their base is a statement.
   is_statement: ->
     @base.is_statement and @base.is_statement() and not @has_properties()
+  
+  # Works out if the value is the start of a chain.
+  is_start: (o) ->
+    return true if this is o.chain_root and @properties[0] instanceof AccessorNode
+    node: o.chain_root.base or o.chain_root.variable
+    while node instanceof CallNode then node: node.variable
+    node is this
 
   # We compile a value to JavaScript by compiling and joining each property.
   # Things get much more insteresting if the chain of properties has *soak*
@@ -307,19 +314,19 @@ exports.ValueNode: class ValueNode extends BaseNode
     only:         del(o, 'only_first')
     op:           del(o, 'operation')
     props:        if only then @properties[0...@properties.length - 1] else @properties
-    o.chain_root: this unless o.chain_root
+    o.chain_root: or this
     baseline:     @base.compile o
     baseline:     "($baseline)" if @base instanceof ObjectNode and @has_properties()
     complete:     @last: baseline
 
-    for prop in props
+    for prop, i in props
       @source: baseline
       if prop.soak_node
-        if @base instanceof CallNode and prop is props[0]
+        if @base instanceof CallNode and i is 0
           temp: o.scope.free_variable()
-          complete: "($temp = $complete)$@SOAK" + (baseline: temp + prop.compile(o))
+          complete: "(${ baseline: temp } = ($complete))"
-        else
+        complete: "typeof $complete === \"undefined\" || $baseline" if i is 0 and @is_start(o)
-          complete: complete + @SOAK + (baseline: + prop.compile(o))
+        complete: + @SOAK + (baseline: + prop.compile(o))
       else
         part: prop.compile(o)
         baseline: + part

test/test_existence.coffee

@@ -74,3 +74,7 @@ ok result is '10'
 result: not value?.property?
 ok result
 
+
+# Safely calls values off of non-existent variables.
+result: nothing?.value
+ok result is undefined