Merge pull request #48 from petermlm/master

Get children by tag

examples/tree_traversal.c

@@ -0,0 +1,73 @@
+#include "../mpc.h"
+
+int main(int argc, char *argv[]) {
+
+  mpc_parser_t *Input  = mpc_new("input");
+  mpc_parser_t *Node  = mpc_new("node");
+  mpc_parser_t *Leaf  = mpc_new("leaf");
+  mpc_ast_t *ast, *tree, *child, *child_sub;
+  mpc_result_t r;
+  int index, lb;
+
+  mpca_lang(MPCA_LANG_PREDICTIVE,
+        " node : '(' <node> ',' /foo/ ',' <node> ')' | <leaf>;"
+        " leaf : /bar/;"
+        " input : /^/ <node> /$/;",
+        Node, Leaf, Input, NULL);
+
+  if (argc > 1) {
+
+    if (mpc_parse_contents(argv[1], Input, &r)) {
+      ast = r.output;
+    } else {
+      mpc_err_print(r.error);
+      mpc_err_delete(r.error);
+      mpc_cleanup(3, Node, Leaf, Input);
+      return EXIT_FAILURE;
+    }
+
+  } else {
+
+    if (mpc_parse_pipe("<stdin>", stdin, Input, &r)) {
+      ast = r.output;
+    } else {
+      mpc_err_print(r.error);
+      mpc_err_delete(r.error);
+      mpc_cleanup(3, Node, Leaf, Input);
+      return EXIT_FAILURE;
+    }
+
+  }
+
+  /* Get index or child of tree */
+  tree = ast->children[1];
+
+  index = mpc_ast_get_index(tree, "node|>");
+  child = mpc_ast_get_child(tree, "node|>");
+
+  if(child == NULL) {
+    mpc_cleanup(3, Node, Leaf, Input);
+    mpc_ast_delete(ast);
+    return EXIT_FAILURE;
+  }
+
+  printf("Index: %d; Child: \"%s\"\n", index, child->tag);
+
+  /* Get multiple indexes or children of trees */
+  index     = mpc_ast_get_index_lb(child, "node|leaf|regex", 0);
+  child_sub = mpc_ast_get_child_lb(child, "node|leaf|regex", 0);
+
+  while(index != -1) {
+    printf("-- Index: %d; Child: \"%s\"\n", index, child_sub->tag);
+
+    lb = index + 1;
+    index     = mpc_ast_get_index_lb(child, "node|leaf|regex", lb);
+    child_sub = mpc_ast_get_child_lb(child, "node|leaf|regex", lb);
+  }
+
+  /* Clean up and return */
+  mpc_cleanup(3, Node, Leaf, Input);
+  mpc_ast_delete(ast);
+
+  return EXIT_SUCCESS;
+}

mpc.c

@@ -2776,6 +2776,38 @@ void mpc_ast_print_to(mpc_ast_t *a, FILE *fp) {
   mpc_ast_print_depth(a, 0, fp);
 }
 
+int mpc_ast_get_index(mpc_ast_t *ast, const char *tag) {
+  return mpc_ast_get_index_lb(ast, tag, 0);
+}
+
+int mpc_ast_get_index_lb(mpc_ast_t *ast, const char *tag, int lb) {
+  int i;
+
+  for(i=lb; i<ast->children_num; i++) {
+    if(strcmp(ast->children[i]->tag, tag) == 0) {
+      return i;
+    }
+  }
+
+  return -1;
+}
+
+mpc_ast_t *mpc_ast_get_child(mpc_ast_t *ast, const char *tag) {
+  return mpc_ast_get_child_lb(ast, tag, 0);
+}
+
+mpc_ast_t *mpc_ast_get_child_lb(mpc_ast_t *ast, const char *tag, int lb) {
+  int i;
+
+  for(i=lb; i<ast->children_num; i++) {
+    if(strcmp(ast->children[i]->tag, tag) == 0) {
+      return ast->children[i];
+    }
+  }
+
+  return NULL;
+}
+
 mpc_val_t *mpcf_fold_ast(int n, mpc_val_t **xs) {
   
   int i, j;

mpc.h

@@ -276,6 +276,11 @@ void mpc_ast_delete(mpc_ast_t *a);
 void mpc_ast_print(mpc_ast_t *a);
 void mpc_ast_print_to(mpc_ast_t *a, FILE *fp);
 
+int mpc_ast_get_index(mpc_ast_t *ast, const char *tag);
+int mpc_ast_get_index_lb(mpc_ast_t *ast, const char *tag, int lb);
+mpc_ast_t *mpc_ast_get_child(mpc_ast_t *ast, const char *tag);
+mpc_ast_t *mpc_ast_get_child_lb(mpc_ast_t *ast, const char *tag, int lb);
+
 /*
 ** Warning: This function currently doesn't test for equality of the `state` member!
 */