added detach function

src/ast/ast.c

@@ -3,11 +3,12 @@
 #include <stdio.h>
 #include <stdlib.h>
 #include <sys/log.h>
+#include <assert.h>
 
-struct AST_Node_t *AST_new_node(enum AST_SyntaxElement_t kind, const char* value) {
+AST_NODE_PTR AST_new_node(enum AST_SyntaxElement_t kind, const char* value) {
   DEBUG("creating new AST node: %d \"%s\"", kind, value);
 
-  struct AST_Node_t *node = malloc(sizeof(struct AST_Node_t));
+  AST_NODE_PTR node = malloc(sizeof(struct AST_Node_t));
 
   if (node == NULL) {
     PANIC("failed to allocate AST node");
@@ -17,6 +18,7 @@ struct AST_Node_t *AST_new_node(enum AST_SyntaxElement_t kind, const char* value
   node->parent = NULL;
   node->children = NULL;
   node->child_count = 0;
+  node->child_cap = 0;
   node->kind = kind;
   node->value = value;
 
@@ -25,7 +27,7 @@ struct AST_Node_t *AST_new_node(enum AST_SyntaxElement_t kind, const char* value
 
 static const char* lookup_table[AST_ELEMENT_COUNT] = { "__UNINIT__" };
 
-void AST_init() {
+void AST_init(void) {
   DEBUG("initializing global syntax tree...");
 
   INFO("filling lookup table...");
@@ -92,17 +94,24 @@ const char* AST_node_to_string(struct AST_Node_t* node) {
   return string;
 }
 
-void AST_push_node(struct AST_Node_t *owner, struct AST_Node_t *child) {
+#define PRE_ALLOCATION_CNT 10
+
+void AST_push_node(AST_NODE_PTR owner, AST_NODE_PTR child) {
   DEBUG("Adding new node %p to %p", child, owner);
 
+  assert(PRE_ALLOCATION_CNT >= 1);
+
   // if there are no children for now
-  if (owner->child_count == 0) {
+  if (owner->children == NULL) {
+    assert(owner->child_count == 0);
     DEBUG("Allocating new children array");
     owner->children = malloc(sizeof(struct AST_Node_t *));
+    owner->child_cap = 1;
 
-  } else {
-    DEBUG("Rellocating old children array");
-    const size_t size = sizeof(struct AST_Node_t *) * (owner->child_count + 1);
+  } else if (owner->child_count >= owner->child_cap) {
+    DEBUG("Reallocating old children array");
+    owner->child_cap += PRE_ALLOCATION_CNT;
+    const size_t size = sizeof(struct AST_Node_t *) * owner->child_cap;
     owner->children = realloc(owner->children, size);
   }
 
@@ -113,8 +122,8 @@ void AST_push_node(struct AST_Node_t *owner, struct AST_Node_t *child) {
   owner->children[owner->child_count++] = child;
 }
 
-struct AST_Node_t *AST_get_node(struct AST_Node_t *owner, size_t idx) {
-  DEBUG("retrvieng node %d from %p", idx, owner);
+AST_NODE_PTR AST_get_node(AST_NODE_PTR owner, size_t idx) {
+  DEBUG("retrieving node %d from %p", idx, owner);
 
   if (owner == NULL) {
     PANIC("AST owner node is NULL");
@@ -124,7 +133,7 @@ struct AST_Node_t *AST_get_node(struct AST_Node_t *owner, size_t idx) {
     PANIC("AST owner node has no children");
   }
 
-  struct AST_Node_t *child = owner->children[idx];
+  AST_NODE_PTR child = owner->children[idx];
 
   if (child == NULL) {
     PANIC("child node is NULL");
@@ -133,20 +142,48 @@ struct AST_Node_t *AST_get_node(struct AST_Node_t *owner, size_t idx) {
   return child;
 }
 
-void AST_delete_node(struct AST_Node_t *node) {
-  DEBUG("Deleting AST node: %p", node);
+void AST_delete_node(AST_NODE_PTR node) {
+    DEBUG("Deleting AST node: %p", node);
 
-  if (node == NULL) {
-    PANIC("Node to free is NULL");
-  }
+    if (node == NULL) {
+        PANIC("Node to free is NULL");
+    }
 
-  if (node->children == NULL) {
-    return;
-  }
+    if (node->parent != NULL) {
+        AST_detach_node(node->parent, node);
+    }
 
-  for (size_t i = 0; i < node->child_count; i++) {
-    AST_delete_node(node->children[i]);
-  }
+    if (node->children == NULL) {
+        return;
+    }
+
+    for (size_t i = 0; i < node->child_count; i++) {
+        if (node->children[i] != node) {
+            AST_delete_node(node->children[i]);
+        } else {
+            WARN("Circular dependency in AST: parent -> child -> parent -> child -> ...");
+        }
+    }
+
+    free(node->children);
+    free(node);
+}
+
+AST_NODE_PTR AST_detach_node(AST_NODE_PTR parent, AST_NODE_PTR child) {
+    assert(parent != NULL);
+    assert(child != NULL);
+
+    for (size_t i = 0; i < parent->child_count; i++) {
+        if (child == parent->children[i]) {
+            memcpy(&parent->children[i], &parent->children[i + 1], parent->child_count - i - 1);
+            parent->child_count--;
+            return child;
+        }
+    }
+
+    WARN("Node not a child of parent");
+
+    return child;
 }
 
 static void __AST_visit_nodes_recurse2(struct AST_Node_t *root,

src/ast/ast.h

@@ -69,6 +69,7 @@ struct AST_Node_t {
   // number of child nodes ownd by this node
   // length of children array
   size_t child_count;
+  size_t child_cap;
   // variable amount of child nodes
   struct AST_Node_t **children;
 };
@@ -90,6 +91,8 @@ void AST_delete_node(struct AST_Node_t *);
 // add a new child node
 void AST_push_node(struct AST_Node_t *owner, struct AST_Node_t *child);
 
+AST_NODE_PTR AST_detach_node(AST_NODE_PTR parent, AST_NODE_PTR child);
+
 // get a specific child node
 struct AST_Node_t *AST_get_node(struct AST_Node_t *owner, size_t idx);