Added simplifying methods

- Prune children to remove unneeded nodes
- resolve constant expressions
- Flatten lists

exercises/03/vslc/src/parser.y

@@ -250,13 +250,13 @@ expression:
       $$ = NODE(EXPRESSION, strdup("~"), 1, $2);
     }
   | '(' expression ')' {
-      $$ = NODE(EXPRESSION, NULL /*strdup("group")*/, 1, $2);
+      $$ = NODE(EXPRESSION, /*NULL*/ strdup("group"), 1, $2);
     }
   | number {
-      $$ = NODE(EXPRESSION, NULL /*strdup("number")*/, 1, $1);
+      $$ = NODE(EXPRESSION, /*NULL*/ strdup("number"), 1, $1);
     }
   | identifier {
-      $$ = NODE(EXPRESSION, NULL /*strdup("identifier")*/, 1, $1);
+      $$ = NODE(EXPRESSION, /*NULL*/ strdup("identifier"), 1, $1);
     }
   | identifier '(' argument_list ')' {
       $$ = NODE(EXPRESSION, /*NULL*/ strdup("function_call"), 2, $1, $3);

exercises/03/vslc/src/tree.c

@@ -33,7 +33,8 @@ tree_print(node_t* root, stem head)
     printf("──%s", node_string[root->type] );
     if ( root->type == IDENTIFIER_DATA ||
          root->type == STRING_DATA ||
-         root->type == EXPRESSION ) 
+         root->type == EXPRESSION ||
+         root->type == RELATION) 
         printf("(%s)", (char *) root->data);
     else if (root->type == NUMBER_DATA)
         printf ( "(%ld)", *((int64_t *)root->data) );
@@ -73,8 +74,8 @@ simplify_syntax_tree ( void )
 void
 print_syntax_tree ( void )
 {
-    node_print ( root, 0 );
-    //tree_print(root, 0);
+    //node_print ( root, 0 );
+    tree_print(root, 0);
 }
 
 // Changed so it returns the pointer to the new node, can be used as before, but makes the parser file cleaner
@@ -144,45 +145,146 @@ destroy_subtree ( node_t *discard )
 }
 
 static void
-prune_children(node_t *parent) 
+prune_children(node_t **simplified, node_t *root) 
 {
-    if (!parent)
+    if (!root)
         return;
 
-    for (int i = 0; i < parent->n_children; i++)
-        prune_children(parent->children[i]);
-    
-    printf("Trying to remove node!\n");
-    if (parent->data != NULL || parent->n_children != 1)
-        return;
-    printf("Only one child found. Purging...\n");
-    
-    node_t *child = parent->children[0];
-    switch (parent->type)
+    node_t *result = root;
+    switch (root->type)
     {
-    case PROGRAM:
+    case GLOBAL:
+    case ARGUMENT_LIST:
+    case PARAMETER_LIST:
     case STATEMENT:
-    case EXPRESSION:
     case PRINT_ITEM:
-        printf("Removing node!\n");
-        //parent->children = NULL;
-        free(parent->children);
+    case PRINT_STATEMENT:
+        result = root->children[0];
+
+        // The print_statement only contains a print_list, still need a print_statement.
+        if (root->type == PRINT_STATEMENT)
+            result->type = PRINT_STATEMENT;
         
-        //node_finalize(parent);
-        parent = child;
-    default:
+        node_finalize(root);
         break;
     }
 
-    /*
-    if (parent->n_children != 1 || parent->data)
+    *simplified = result;
+}
+
+
+static void
+resolve_constant_expressions(node_t **simplified, node_t *root)
+{
+    if (!root)
+        return;
+
+    if (root->type != EXPRESSION)
         return;
     
-    printf("delete parent\n");
-    node_t *child = parent->children[0];
-    //parent->children = NULL;
-    node_finalize(parent);
-    parent = child;*/
+    node_t *result = root;
+    
+    switch (root->n_children)
+    {
+    case 1:
+        result = root->children[0];
+        
+        if (root->data && 
+            result->type == NUMBER_DATA && 
+            result->data)
+        {
+            switch (*((char*)root->data))
+            {
+            case '-':
+                *((int64_t*)result->data) *= -1;
+                break;
+            case '~':
+                *((int64_t*)result->data) = ~*((int64_t*)result->data);
+                break;
+            }
+        }
+
+        node_finalize(root);
+        break;
+    
+    case 2:
+        // Both children needs to be numbers to resolve constants
+        if (root->children[0]->type == NUMBER_DATA && 
+            root->children[1]->type == NUMBER_DATA)
+        {
+            // Check if children does not contain null pointers
+            if (!root->children[0]->data)
+                break;
+            if (!root->children[1]->data)
+                break;
+
+            // Check if data field is not null pointer
+            if (!root->data)
+                break;
+            
+            result = root->children[0];
+            int64_t
+                *lhs = result->data,
+                *rhs = root->children[1]->data;
+
+            switch (*(char*)root->data)
+            {
+            case '|': *lhs |= *rhs; break;
+            case '^': *lhs ^= *rhs; break;
+            case '&': *lhs &= *rhs; break;
+            case '+': *lhs += *rhs; break;
+            case '-': *lhs -= *rhs; break;
+            case '*': *lhs *= *rhs; break;
+            case '/': *lhs /= *rhs; break;
+            }
+
+            node_finalize(root->children[1]);
+            node_finalize(root);
+        }            
+        
+        
+        break;
+    }
+    *simplified = result;
+}
+
+static void
+flatten(node_t **simplified, node_t *root)
+{
+    /* This will flatten left-expanded lists */
+    if (!root)
+        return;
+
+    node_t **new_children, *result = root;
+    switch (root->type)
+    {
+    case GLOBAL_LIST:
+    case STATEMENT_LIST:
+    case PRINT_LIST:
+    case EXPRESSION_LIST:
+    case VARIABLE_LIST:
+    case DECLARATION_LIST:
+        // Check if node have more than two children
+        if (root->n_children < 2)
+            break;
+        
+        result = root->children[0];
+        result->n_children++;
+
+        // Realloc the array of children to the new size 
+        if (!(new_children = realloc(result->children, result->n_children * sizeof(node_t*))))
+            break;
+        // if successs, insert the new array
+        result->children = new_children;
+
+        // Insert child at the end
+        result->children[result->n_children - 1] = root->children[1];
+
+        node_finalize(root);
+        break;
+    }
+
+    *simplified = result;
 }
 
 
@@ -226,6 +328,9 @@ simplify_tree ( node_t **simplified, node_t *root )
     for (int i = 0; i < root->n_children; i++)
         simplify_tree(&root->children[i], root->children[i]);
 
-    prune_children(root);
+    prune_children(&root, root);
+    resolve_constant_expressions(&root, root);
+    flatten(&root, root);
 
+    *simplified = root;
 }

exercises/03/vslc/vsl_programs/ps3-simplify/constants.vsl

@@ -1,8 +1,8 @@
 
 func main() begin
-    var a
-    a := 1 + 2 + 4 + 5 + 6 + 7 + 8 + 9
-    b := (10 + 10 * 4) * (2 + 2 * (1 + 1)) / 10 + 2 * 5 + 6 / 3
+    var a, b, c
+    a := 1 + 2 + 4 + 5 + 6 + 7 + 8 + 9 - 1
+    b := (10 + 10 * 5) * (2 + 2 * (1 + 1)) / 10 + 2 * 5 + 6 / 3
 
     if a = b then
         print "The answer is", b