Implemented left recursion descent parser

1 files changed, 60 insertions, 0 deletions

diff --git a/tree.c b/tree.c
new file mode 100644
index 0000000..e5fc435
--- /dev/null
+++ b/tree.c
@@ -0,0 +1,60 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include "tree.h"
+
+int strichar(const char *str, char c){
+  for(int i=0; str[i]!='\0';i++){
+    if(str[i] == c) return i;
+  }
+  return -1; //char not found
+}
+const char ops[] = {'+','*','!'}; //ordem inversa
+const int opsize = sizeof(ops)/sizeof(char);
+node * parse(char *str) { //expects a string with no whitespace
+
+  int j,i;
+  for(i=0; i<opsize; i++){
+    j=strichar(str,ops[i]);
+    if(j>=0) break;
+  }
+
+  node *this = (node *)malloc(sizeof(node));
+
+  if(j<0) {
+    this->type = LTTR;
+    this->el = str[0];
+  }
+
+  else{
+    this->el = ops[i];
+    if(i==2) {
+      this->type = UNOP;
+      this->child[0] = parse(str+j+1);
+    }
+    else {
+      str[j] = '\0';
+      this->type = BIOP;
+      this->child[0] = parse(str);
+      this->child[1] = parse(str+j+1);
+    }
+  }
+  return this;
+}
+
+void printTree(node *root, int level) {
+  if (root == NULL)
+    return;
+
+  if (level) {
+    for (int i = 1; i < level; i++) {
+      printf("│  ");
+    }
+    printf("├─ ");
+  }
+  printf("%c\n", root->el);
+  for (int i = 0; i < 2; i++) {
+    if (root->child[i] != NULL) {
+      printTree(root->child[i], level + 1);
+    }
+  }
+}