Begin adding index assignment

src/abstract_tree/assignment.rs

@@ -19,6 +19,8 @@ pub enum AssignmentOperator {
 
 impl AbstractTree for Assignment {
     fn from_syntax_node(source: &str, node: Node) -> Result<Self> {
+        Error::expect_syntax_node(source, "assignment", node)?;
+
         let identifier_node = node.child(0).unwrap();
         let identifier = Identifier::from_syntax_node(source, identifier_node)?;
 

src/abstract_tree/index.rs

@@ -5,9 +5,9 @@ use crate::{AbstractTree, Error, Expression, List, Map, Result, Value};
 
 #[derive(Debug, Clone, Serialize, Deserialize, Eq, PartialEq, PartialOrd, Ord)]
 pub struct Index {
-    collection: Expression,
+    pub collection: Expression,
-    index: Expression,
+    pub index: Expression,
-    index_end: Option<Expression>,
+    pub index_end: Option<Expression>,
 }
 
 impl AbstractTree for Index {
@@ -50,7 +50,7 @@ impl AbstractTree for Index {
 
                 Ok(item)
             }
-            Value::Map(mut map) => {
+            Value::Map(map) => {
                 let value = if let Expression::Identifier(identifier) = &self.index {
                     let key = identifier.inner();
 

src/abstract_tree/index_assignment.rs

@@ -19,6 +19,8 @@ pub enum AssignmentOperator {
 
 impl AbstractTree for IndexAssignment {
     fn from_syntax_node(source: &str, node: Node) -> Result<Self> {
+        Error::expect_syntax_node(source, "index_assignment", node)?;
+
         let index_node = node.child(0).unwrap();
         let index = Index::from_syntax_node(source, index_node)?;
 
@@ -48,14 +50,43 @@ impl AbstractTree for IndexAssignment {
     }
 
     fn run(&self, source: &str, context: &mut Map) -> Result<Value> {
-        let mut left = self.index.run(source, context)?;
+        let index_collection = self.index.collection.run(source, context)?;
-        let right = self.statement.run(source, context)?;
+        let index_context = index_collection.as_map().unwrap_or(&context);
+        let index_key = if let crate::Expression::Identifier(identifier) = &self.index.index {
+            identifier.inner()
+        } else {
+            return Err(Error::VariableIdentifierNotFound(
+                self.index.index.run(source, context)?.to_string(),
+            ));
+        };
 
-        match self.operator {
+        let value = self.statement.run(source, &mut context.clone())?;
-            AssignmentOperator::PlusEqual => left += right,
+
-            AssignmentOperator::MinusEqual => left -= right,
+        let new_value = match self.operator {
-            AssignmentOperator::Equal => left = right,
+            AssignmentOperator::PlusEqual => {
+                if let Some(mut previous_value) = index_context.variables()?.get(index_key).cloned()
+                {
+                    previous_value += value;
+                    previous_value
+                } else {
+                    Value::Empty
                 }
+            }
+            AssignmentOperator::MinusEqual => {
+                if let Some(mut previous_value) = index_context.variables()?.get(index_key).cloned()
+                {
+                    previous_value -= value;
+                    previous_value
+                } else {
+                    Value::Empty
+                }
+            }
+            AssignmentOperator::Equal => value,
+        };
+
+        context
+            .variables_mut()?
+            .insert(index_key.clone(), new_value);
 
         Ok(Value::Empty)
     }

src/abstract_tree/mod.rs

@@ -17,6 +17,7 @@ pub mod function_call;
 pub mod identifier;
 pub mod if_else;
 pub mod index;
+pub mod index_assignment;
 pub mod insert;
 pub mod logic;
 pub mod r#match;
@@ -30,8 +31,9 @@ pub mod r#while;
 
 pub use {
     assignment::*, block::*, built_in_function::*, expression::*, filter::*, find::*,
-    function_call::*, identifier::*, if_else::*, index::*, insert::*, logic::*, math::*, r#for::*,
+    function_call::*, identifier::*, if_else::*, index::*, index_assignment::*, insert::*,
-    r#match::*, r#while::*, remove::*, select::*, statement::*, transform::*, value_node::*,
+    logic::*, math::*, r#for::*, r#match::*, r#while::*, remove::*, select::*, statement::*,
+    transform::*, value_node::*,
 };
 
 use tree_sitter::Node;

src/abstract_tree/statement.rs

@@ -2,8 +2,8 @@ use serde::{Deserialize, Serialize};
 use tree_sitter::Node;
 
 use crate::{
-    AbstractTree, Assignment, Block, Error, Expression, Filter, Find, For, IfElse, Insert, Map,
+    AbstractTree, Assignment, Block, Error, Expression, Filter, Find, For, IfElse, IndexAssignment,
-    Match, Remove, Result, Select, Transform, Value, While,
+    Insert, Map, Match, Remove, Result, Select, Transform, Value, While,
 };
 
 /// Abstract representation of a statement.
@@ -25,12 +25,11 @@ pub enum Statement {
     Remove(Box<Remove>),
     Select(Box<Select>),
     Insert(Box<Insert>),
+    IndexAssignment(Box<IndexAssignment>),
 }
 
 impl AbstractTree for Statement {
     fn from_syntax_node(source: &str, node: Node) -> Result<Self> {
-        debug_assert_eq!("statement", node.kind());
-
         let child = node.child(0).unwrap();
 
         match child.kind() {
@@ -73,12 +72,14 @@ impl AbstractTree for Statement {
             "insert" => Ok(Statement::Insert(Box::new(Insert::from_syntax_node(
                 source, child,
             )?))),
-            _ => Err(Error::UnexpectedSyntaxNode {
+            "index_assignment" => Ok(Statement::IndexAssignment(Box::new(IndexAssignment::from_syntax_node(
-                expected: "assignment, expression, if...else, while, for, transform, filter, tool, async, find, remove, select or insert",
+                source, child,
-                actual: child.kind(),
+            )?))),
-                location: child.start_position(),
+            _ => Err(Error::expect_syntax_node(
-                relevant_source: source[child.byte_range()].to_string(),
+                source,
-            }),
+                "assignment, expression, if...else, while, for, transform, filter, tool, async, find, remove, select, insert or index_assignment",    
+                child
+            ).unwrap_err())
         }
     }
 
@@ -97,6 +98,7 @@ impl AbstractTree for Statement {
             Statement::Remove(remove) => remove.run(source, context),
             Statement::Select(select) => select.run(source, context),
             Statement::Insert(insert) => insert.run(source, context),
+            Statement::IndexAssignment(index_assignment) => index_assignment.run(source, context),
         }
     }
 }

tree-sitter-dust/corpus/assignment.txt

@@ -25,7 +25,7 @@ x:y = 1
 
 (root
   (statement
-    (assignment
+    (index_assignment
       (index
         (expression
           (identifier))
@@ -47,7 +47,7 @@ x:9 = 'foobar'
 
 (root
   (statement
-    (assignment
+    (index_assignment
       (index
         (expression
           (identifier))

tree-sitter-dust/grammar.js

@@ -21,7 +21,7 @@ module.exports = grammar({
       '}',
     ),
 
-    statement: $ => prec.right(seq(
+    statement: $ => prec.left(seq(
       choice(
         $.assignment,
         $.block,
@@ -30,6 +30,7 @@ module.exports = grammar({
         $.find,
         $.for,
         $.if_else,
+        $.index_assignment,
         $.insert,
         $.match,
         $.reduce,
@@ -153,10 +154,13 @@ module.exports = grammar({
     ),
 
     assignment: $ => seq(
-      choice(
       $.identifier,
-        $.index,
+      $.assignment_operator,
+      $.statement,
     ),
+
+    index_assignment: $ => seq(
+      $.index,
       $.assignment_operator,
       $.statement,
     ),

tree-sitter-dust/src/grammar.json

@@ -50,7 +50,7 @@
       ]
     },
     "statement": {
-      "type": "PREC_RIGHT",
+      "type": "PREC_LEFT",
       "value": 0,
       "content": {
         "type": "SEQ",
@@ -86,6 +86,10 @@
                 "type": "SYMBOL",
                 "name": "if_else"
               },
+              {
+                "type": "SYMBOL",
+                "name": "index_assignment"
+              },
               {
                 "type": "SYMBOL",
                 "name": "insert"
@@ -706,9 +710,6 @@
     },
     "assignment": {
       "type": "SEQ",
-      "members": [
-        {
-          "type": "CHOICE",
       "members": [
         {
           "type": "SYMBOL",
@@ -716,10 +717,21 @@
         },
         {
           "type": "SYMBOL",
-              "name": "index"
+          "name": "assignment_operator"
+        },
+        {
+          "type": "SYMBOL",
+          "name": "statement"
         }
       ]
     },
+    "index_assignment": {
+      "type": "SEQ",
+      "members": [
+        {
+          "type": "SYMBOL",
+          "name": "index"
+        },
         {
           "type": "SYMBOL",
           "name": "assignment_operator"

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

@@ -15,10 +15,6 @@
           "type": "identifier",
           "named": true
         },
-        {
-          "type": "index",
-          "named": true
-        },
         {
           "type": "statement",
           "named": true
@@ -348,6 +344,29 @@
       ]
     }
   },
+  {
+    "type": "index_assignment",
+    "named": true,
+    "fields": {},
+    "children": {
+      "multiple": true,
+      "required": true,
+      "types": [
+        {
+          "type": "assignment_operator",
+          "named": true
+        },
+        {
+          "type": "index",
+          "named": true
+        },
+        {
+          "type": "statement",
+          "named": true
+        }
+      ]
+    }
+  },
   {
     "type": "insert",
     "named": true,
@@ -588,6 +607,10 @@
           "type": "if_else",
           "named": true
         },
+        {
+          "type": "index_assignment",
+          "named": true
+        },
         {
           "type": "insert",
           "named": true