Присваивание как выражение

Author: aNNiMON

program.own

@@ -217,4 +217,7 @@ def funcWithOptionalArgs(str, count = 5, prefix = "<", suffix = ">") = prefix +
 
 println funcWithOptionalArgs("*")
 println funcWithOptionalArgs("+", 2)
-println funcWithOptionalArgs("*", 10, "<!")
+println funcWithOptionalArgs("*", 10, "<!")
+
+v1 = v2 = v3 = v4 = 5
+echo(v1, v2, v3, v4)

src/com/annimon/ownlang/parser/Parser.java

@@ -87,27 +87,19 @@ private Statement statement() {
         if (match(TokenType.MATCH)) {
             return new ExprStatement(match());
         }
-        if (match(TokenType.EXTRACT)) {
-            return destructuringAssignment();
-        }
         if (lookMatch(0, TokenType.WORD) && lookMatch(1, TokenType.LPAREN)) {
             return new ExprStatement(function(qualifiedName()));
         }
         return assignmentStatement();
     }
 
     private Statement assignmentStatement() {
-        if (lookMatch(0, TokenType.WORD) && lookMatch(1, TokenType.EQ)) {
-            final String variable = consume(TokenType.WORD).getText();
-            consume(TokenType.EQ);
-            return new AssignmentStatement(variable, expression());
+        if (match(TokenType.EXTRACT)) {
+            return destructuringAssignment();
         }
-        
-        final Expression qualifiedNameExpr = qualifiedName();
-        if (lookMatch(0, TokenType.EQ) && (qualifiedNameExpr instanceof ContainerAccessExpression)) {
-            consume(TokenType.EQ);
-            final ContainerAccessExpression containerExpr = (ContainerAccessExpression) qualifiedNameExpr;
-            return new ContainerAssignmentStatement(containerExpr, expression());
+        final Expression assignment = assignmentStrict();
+        if (assignment != null) {
+            return new ExprStatement(assignment);
         }
         throw new ParseException("Unknown statement: " + get(0));
     }
@@ -330,9 +322,36 @@ private MatchExpression match() {
     }
 
     private Expression expression() {
+        return assignment();
+    }
+    
+    private Expression assignment() {
+        final Expression assignment = assignmentStrict();
+        if (assignment != null) {
+            return assignment;
+        }
         return ternary();
     }
 
+    private Expression assignmentStrict() {
+        if (lookMatch(0, TokenType.WORD) && lookMatch(1, TokenType.EQ)) {
+            final String variable = consume(TokenType.WORD).getText();
+            consume(TokenType.EQ);
+            return new AssignmentExpression(variable, expression());
+        }
+        
+        final int position = pos;
+        final Expression qualifiedNameExpr = qualifiedName();
+        if (lookMatch(0, TokenType.EQ) && (qualifiedNameExpr instanceof ContainerAccessExpression)) {
+            consume(TokenType.EQ);
+            final ContainerAccessExpression containerExpr = (ContainerAccessExpression) qualifiedNameExpr;
+            return new ContainerAssignmentExpression(containerExpr, expression());
+        }
+        pos = position;
+        
+        return null;
+    }
+    
     private Expression ternary() {
         Expression result = logicalOr();
 

src/com/annimon/ownlang/parser/ast/AssignmentStatement.java renamed to src/com/annimon/ownlang/parser/ast/AssignmentExpression.java

@@ -7,20 +7,21 @@
  *
  * @author aNNiMON
  */
-public final class AssignmentStatement implements Statement {
+public final class AssignmentExpression implements Expression {
 
     public final String variable;
     public final Expression expression;
 
-    public AssignmentStatement(String variable, Expression expression) {
+    public AssignmentExpression(String variable, Expression expression) {
         this.variable = variable;
         this.expression = expression;
     }
 
     @Override
-    public void execute() {
+    public Value eval() {
         final Value result = expression.eval();
         Variables.set(variable, result);
+        return result;
     }
 
     @Override

src/com/annimon/ownlang/parser/ast/ContainerAssignmentStatement.java renamed to src/com/annimon/ownlang/parser/ast/ContainerAssignmentExpression.java

@@ -10,29 +10,33 @@
  *
  * @author aNNiMON
  */
-public final class ContainerAssignmentStatement implements Statement {
+public final class ContainerAssignmentExpression implements Expression {
 
     public final ContainerAccessExpression containerExpr;
     public final Expression expression;
 
-    public ContainerAssignmentStatement(ContainerAccessExpression array, Expression expression) {
+    public ContainerAssignmentExpression(ContainerAccessExpression array, Expression expression) {
         this.containerExpr = array;
         this.expression = expression;
     }
 
     @Override
-    public void execute() {
+    public Value eval() {
         final Value container = containerExpr.getContainer();
         final Value lastIndex = containerExpr.lastIndex();
         switch (container.type()) {
-            case Types.ARRAY:
+            case Types.ARRAY: {
+                final Value result = expression.eval();
                 final int arrayIndex = (int) lastIndex.asNumber();
-                ((ArrayValue) container).set(arrayIndex, expression.eval());
-                return;
+                ((ArrayValue) container).set(arrayIndex, result);
+                return result;
+            }
 
-            case Types.MAP:
-                ((MapValue) container).set(lastIndex, expression.eval());
-                return;
+            case Types.MAP: {
+                final Value result = expression.eval();
+                ((MapValue) container).set(lastIndex, result);
+                return result;
+            }
 
             default:
                 throw new TypeException("Array or map expected. Got " + container.type());

src/com/annimon/ownlang/parser/ast/Visitor.java

@@ -7,13 +7,13 @@
 public interface Visitor {
 
     void visit(ArrayExpression s);
-    void visit(AssignmentStatement s);
+    void visit(AssignmentExpression s);
     void visit(BinaryExpression s);
     void visit(BlockStatement s);
     void visit(BreakStatement s);
     void visit(ConditionalExpression s);
     void visit(ContainerAccessExpression s);
-    void visit(ContainerAssignmentStatement s);
+    void visit(ContainerAssignmentExpression s);
     void visit(ContinueStatement s);
     void visit(DoWhileStatement s);
     void visit(DestructuringAssignmentStatement s);

src/com/annimon/ownlang/parser/visitors/AbstractVisitor.java

@@ -18,7 +18,7 @@ public void visit(ArrayExpression s) {
     }
 
     @Override
-    public void visit(AssignmentStatement s) {
+    public void visit(AssignmentExpression s) {
         s.expression.accept(this);
     }
 
@@ -53,7 +53,7 @@ public void visit(ContainerAccessExpression s) {
     }
 
     @Override
-    public void visit(ContainerAssignmentStatement s) {
+    public void visit(ContainerAssignmentExpression s) {
         s.containerExpr.accept(this);
         s.expression.accept(this);
     }

src/com/annimon/ownlang/parser/visitors/AssignValidator.java

@@ -10,7 +10,7 @@
 public final class AssignValidator extends AbstractVisitor {
 
     @Override
-    public void visit(AssignmentStatement s) {
+    public void visit(AssignmentExpression s) {
         super.visit(s);
         if (Variables.isExists(s.variable)) {
             throw new RuntimeException("Cannot assign value to constant");

src/com/annimon/ownlang/parser/visitors/VariablePrinter.java

@@ -9,7 +9,7 @@
 public final class VariablePrinter extends AbstractVisitor {
 
     @Override
-    public void visit(AssignmentStatement s) {
+    public void visit(AssignmentExpression s) {
         super.visit(s);
         System.out.println(s.variable);
     }