added function to convert AST to graphviz diagram

src/ast/ast.c

@@ -1,10 +1,11 @@
 
 #include <ast/ast.h>
+#include <bits/posix2_lim.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <sys/log.h>
 
-struct AST_Node_t *AST_new_node(void) {
+struct AST_Node_t *AST_new_node(enum AST_SyntaxElement_t kind, const char* value) {
   struct AST_Node_t *node = malloc(sizeof(struct AST_Node_t));
 
   if (node == NULL) {
@@ -15,10 +16,36 @@ struct AST_Node_t *AST_new_node(void) {
   node->parent = NULL;
   node->children = NULL;
   node->child_count = 0;
+  node->kind = kind;
+  node->value = value;
 
   return node;
 }
 
+const char* AST_node_to_string(struct AST_Node_t* node) {
+  const char* string = "unknown";
+
+  switch (node->kind) {
+    case AST_Expression:
+      string = "expression";
+      break;
+    case AST_Statement:
+      string = "statement";
+      break;
+    case AST_Branch:
+      string = "if";
+      break;
+    case AST_IntegerLiteral:
+      string = node->value;
+      break;
+    case AST_OperatorAdd:
+      string = "+";
+      break;
+  }
+
+  return string;
+}
+
 void AST_push_node(struct AST_Node_t *owner, struct AST_Node_t *child) {
   // if there are no children for now
   if (owner->child_count == 0) {
@@ -54,8 +81,16 @@ 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 *_) {
+void AST_delete_node(struct AST_Node_t *node) {
-#warning "FIXME: not implemented"
+  if (node == NULL) {
+    PANIC("Node to free is NULL");
+  }
+
+  if (node->children != NULL) {
+    for (size_t i = 0; i < node->child_count; i++) {
+      AST_delete_node(node->children[i]);
+    }
+  }
 }
 
 static void __AST_visit_nodes_recurse2(struct AST_Node_t *root,
@@ -74,3 +109,33 @@ void AST_visit_nodes_recurse(struct AST_Node_t *root,
                                               size_t depth)) {
   __AST_visit_nodes_recurse2(root, for_each, 0);
 }
+
+void AST_fprint_graphviz_node_definition(FILE* stream, struct AST_Node_t* node) {
+
+  fprintf(stream, "\tnode%p [label=\"%s\"]\n", (void*) node, AST_node_to_string(node));
+
+  if (node->children != NULL) {
+    for (size_t i = 0; i < node->child_count; i++) {
+      AST_fprint_graphviz_node_definition(stream, node->children[i]);
+    }
+  }
+}
+
+void AST_fprint_graphviz_node_connection(FILE* stream, struct AST_Node_t* node) {
+
+  if (node->children != NULL) {
+    for (size_t i = 0; i < node->child_count; i++) {
+      fprintf(stream, "\tnode%p -- node%p\n", (void*) node, (void*) node->children[i]);
+      AST_fprint_graphviz_node_connection(stream, node->children[i]);
+    }
+  }
+}
+
+void AST_fprint_graphviz(FILE* stream, struct AST_Node_t* root) {
+  fprintf(stream, "graph {\n");
+
+  AST_fprint_graphviz_node_definition(stream, root);
+  AST_fprint_graphviz_node_connection(stream, root);
+
+  fprintf(stream, "}\n");
+}

src/ast/ast.h

@@ -4,10 +4,24 @@
 
 #include <stdio.h>
 
+// Syntax elements which are stored in a syntax tree
+enum AST_SyntaxElement_t {
+  AST_Statement,
+  AST_Expression,
+  AST_Branch,
+  AST_OperatorAdd,
+  AST_IntegerLiteral
+};
+
 struct AST_Node_t {
   // parent node that owns this node
   struct AST_Node_t *parent;
 
+  // type of AST node: if, declration, ...
+  enum AST_SyntaxElement_t kind;
+  // optional value: integer literal, string literal, ...
+  const char* value;
+
   // number of child nodes ownd by this node
   // length of children array
   size_t child_count;
@@ -15,8 +29,12 @@ struct AST_Node_t {
   struct AST_Node_t **children;
 };
 
+// return a string representation of the nodes type and its value
+// does not take into account its children or parent
+const char* AST_node_to_string(struct AST_Node_t* node);
+
 // create a new initialized (empty) node
-struct AST_Node_t *AST_new_node(void);
+struct AST_Node_t *AST_new_node(enum AST_SyntaxElement_t kind, const char* value);
 
 void AST_delete_node(struct AST_Node_t *);
 
@@ -32,4 +50,7 @@ void AST_visit_nodes_recurse(struct AST_Node_t *root,
                              void (*for_each)(struct AST_Node_t *node,
                                               size_t depth));
 
+// print a graphviz diagram of the supplied node (as root node) into stream
+void AST_fprint_graphviz(FILE* stream, struct AST_Node_t* node);
+
 #endif

src/main.c

@@ -1,3 +1,5 @@
+#include <ast/ast.h>
+#include <stdio.h>
 #include <stdlib.h>
 #include <sys/log.h>
 #include <yacc/parser.tab.h>
@@ -36,6 +38,26 @@ void setup(void)
 int main(void) {
     setup();
 
-    yyparse();
+    struct AST_Node_t* node = AST_new_node(AST_Branch, NULL);
+
+    struct AST_Node_t* child = AST_new_node(AST_OperatorAdd, NULL);
+    AST_push_node(child, AST_new_node(AST_IntegerLiteral, "43"));
+    AST_push_node(child, AST_new_node(AST_IntegerLiteral, "9"));
+
+    AST_push_node(node, child);
+    AST_push_node(node, AST_new_node(AST_Expression, NULL));
+    AST_push_node(node, AST_new_node(AST_Expression, NULL));
+
+    FILE* out = fopen("ast.gv", "w+");
+    // convert this file        ^^^^^^
+    // to an svg with: `dot -Tsvg ast.gv > graph.svg`
+
+    AST_fprint_graphviz(out, node);
+
+    AST_delete_node(node);
+
+    fflush(out);
+    fclose(out);
+
     return 0;
 }