Add index assignment syntax

examples/fizzbuzz.ds

@@ -5,13 +5,13 @@ while count <= 15 {
 	divides_by_5 = count % 5 == 0
 
 	if divides_by_3 && divides_by_5 { 
-		output 'fizzbuzz'
+		(output 'fizzbuzz')
 	} else if divides_by_3 { 
-		output 'fizz'
+		(output 'fizz')
 	} else if divides_by_5 {
-		output 'buzz'
+		(output 'buzz')
 	} else { 
-		output count
+		(output count)
 	}
 	
 	count += 1

examples/sea_creatures.ds

@@ -8,11 +8,11 @@ data = {
 }
 
 for creature in sea_creatures {
-	data.creatures += creature.name
+	data:creatures += creature:name
-	data.total_clams += creature.clams
+	data:total_clams += creature:clams
 
-	if creature.type == 'dolphin' {
+	if creature:type == 'dolphin' {
-		data.dolphin_clams += creature.clams
+		data:dolphin_clams += creature:clams
 	}
 }
 

src/abstract_tree/index.rs

@@ -33,9 +33,9 @@ impl AbstractTree for Index {
     }
 
     fn run(&self, source: &str, context: &mut Map) -> Result<Value> {
-        let value = self.collection.run(source, context)?;
+        let collection = self.collection.run(source, context)?;
 
-        match value {
+        match collection {
             Value::List(list) => {
                 let index = self.index.run(source, context)?.as_integer()? as usize;
 
@@ -56,7 +56,7 @@ impl AbstractTree for Index {
 
                     map.variables()?.get(key).cloned().unwrap_or(Value::Empty)
                 } else {
-                    let value = self.index.run(source, &mut map)?;
+                    let value = self.index.run(source, context)?;
                     let key = value.as_string()?;
 
                     map.variables()?.get(key).cloned().unwrap_or(Value::Empty)
@@ -70,7 +70,7 @@ impl AbstractTree for Index {
 
                 Ok(Value::String(item.to_string()))
             }
-            _ => Err(Error::ExpectedCollection { actual: value }),
+            _ => Err(Error::ExpectedCollection { actual: collection }),
         }
     }
 }

tree-sitter-dust/corpus/assignment.txt

@@ -0,0 +1,61 @@
+================================================================================
+Simple Assignment
+================================================================================
+
+x = y
+
+--------------------------------------------------------------------------------
+
+(root
+  (statement
+    (assignment
+      (identifier)
+      (assignment_operator)
+      (statement
+        (expression
+          (identifier))))))
+
+================================================================================
+Map Item Assignment
+================================================================================
+
+x:y = 1
+
+--------------------------------------------------------------------------------
+
+(root
+  (statement
+    (assignment
+      (index
+        (expression
+          (identifier))
+        (expression
+          (identifier)))
+      (assignment_operator)
+      (statement
+        (expression
+          (value
+            (integer)))))))
+
+================================================================================
+List Item Assignment
+================================================================================
+
+x:9 = 'foobar'
+
+--------------------------------------------------------------------------------
+
+(root
+  (statement
+    (assignment
+      (index
+        (expression
+          (identifier))
+        (expression
+          (value
+            (integer))))
+      (assignment_operator)
+      (statement
+        (expression
+          (value
+            (string)))))))

tree-sitter-dust/grammar.js

@@ -153,7 +153,10 @@ module.exports = grammar({
     ),
 
     assignment: $ => seq(
-      $.identifier,
+      choice(
+        $.identifier,
+        $.index,
+      ),
       $.assignment_operator,
       $.statement,
     ),

tree-sitter-dust/src/grammar.json

@@ -708,8 +708,17 @@
       "type": "SEQ",
       "members": [
         {
-          "type": "SYMBOL",
+          "type": "CHOICE",
-          "name": "identifier"
+          "members": [
+            {
+              "type": "SYMBOL",
+              "name": "identifier"
+            },
+            {
+              "type": "SYMBOL",
+              "name": "index"
+            }
+          ]
         },
         {
           "type": "SYMBOL",

tree-sitter-dust/src/node-types.json

@@ -15,6 +15,10 @@
           "type": "identifier",
           "named": true
         },
+        {
+          "type": "index",
+          "named": true
+        },
         {
           "type": "statement",
           "named": true