Create interp.y

interp.y

@@ -0,0 +1,160 @@
+%{
+#include <stdio.h>
+#include <stdlib.h>
+void yyerror(const char* msg) {}
+extern FILE* yyin;
+
+typedef enum
+{null, opera, var, val} NodeType;
+
+typedef struct Node {
+float val;
+char * name; // val_name
+char * opr; // operator
+NodeType node_type;
+struct Node * left;
+struct Node * right;
+} Node;
+
+Node create_op_node(char * op){
+Node node;
+node.opr = op;
+node.node_type = opera;
+return node;
+}
+
+Node create_var_node(char * op){
+Node node;
+node.name = op;
+node.node_type = var;
+return node;
+}
+
+Node create_val_node(float value){
+Node node;
+node.val = value;
+node.node_type = val;
+return node;
+}
+void connect_node(Node* op, Node* l, Node* r){
+op->left = l;
+op->right = r;
+}
+
+char * var_name = "";
+
+void run_through_tree (Node *node){
+    switch (node->node_type){
+        case var:
+            printf("varable name:%s\n",node->name);
+            break;
+        case val:
+            printf("num value:%f\n",node->val);
+            break;
+        case opera:
+            printf("\noperator:%s\n",node->opr);
+            printf("LFS\n");
+            run_through_tree(node->left);
+            printf("RHS\n");
+            run_through_tree(node->right);
+    }
+
+}
+
+float eval_node(float var_val, Node * node){
+    switch ((*node).node_type){
+        case var:
+            if (var_name == ""){
+                var_name = node->name;
+                printf("%s",node->name);
+                return var_val;
+            }
+            else if (var_name == node->name){
+                return var_val;
+            }
+            else{
+                printf("Error: Too many variable, eg. %s, %s.\n",
+                    var_name,node->name);
+                break;
+            }
+
+
+            break;
+        case val:
+            return (*node).val;
+            break;
+        case opera:
+            if (node->opr == "+"){
+                    return (eval_node(var_val,node->left) + eval_node(var_val,node->right));
+            }
+            else if (node->opr == "-"){
+                    return (eval_node(var_val,node->left) - eval_node(var_val,node->right));
+            }
+            else if (node->opr == "*"){
+                    return (eval_node(var_val,node->left) * eval_node(var_val,node->right));
+            }
+            else if (node->opr == "/"){
+                    return (eval_node(var_val,node->left) / eval_node(var_val,node->right));
+            }
+            break;
+    }
+}
+
+Node * main_node;
+
+
+%}
+
+%union{
+    float floatVal;
+    int   intVal;
+    char * strVal;
+    struct Node *node;
+}
+
+%token T_VAR
+%token T_NUM
+%token T_ADD T_SUB T_MUL T_DIV T_LPATH T_RPATH T_NEWLINE
+%left T_ADD T_SUB
+%left T_MUL T_DIV
+%left NEG
+
+%type <floatVal> T_NUM
+%type <strVal> T_VAR
+%type <node> E
+
+
+%%
+
+S    : S E T_NEWLINE { main_node = $2;run_through_tree(main_node); /*printf("TOTAL_VALUE: %f",eval_node(5.0,main_node));*/}
+     | {}
+     ;
+
+E    :  E T_ADD E {Node * op_node = (Node *) malloc(sizeof(Node));*op_node = create_op_node("+"); connect_node(op_node,$1,$3);$$ = op_node;}
+     |  E T_SUB E {Node * op_node = (Node *) malloc(sizeof(Node));*op_node = create_op_node("-"); connect_node(op_node,$1,$3);$$ = op_node;}
+     |  E T_MUL E {Node * op_node 
+= (Node *) malloc(sizeof(Node));*op_node = create_op_node("*"); connect_node(op_node,$1,$3);$$ = op_node;}
+     |  E T_DIV E {Node * op_node = (Node *) malloc(sizeof(Node));*op_node = create_op_node("/"); connect_node(op_node,$1,$3);$$ = op_node;} 
+     | T_SUB E %prec NEG {
+                        Node * op_node = (Node *) malloc(sizeof(Node));
+                        Node * zero_node = (Node *) malloc(sizeof(Node));
+                        * zero_node = create_val_node(0.0);
+                        * op_node = create_op_node("-");
+                        connect_node(op_node,zero_node,$2);
+                        $$ = op_node;}
+     | T_NUM {Node * val_node = (Node *) malloc(sizeof(Node));* val_node = create_val_node($1); $$ = val_node;}
+     | T_VAR {Node * var_node = (Node *) malloc(sizeof(Node));* var_node = create_var_node($1); $$ = var_node;}
+     | T_LPATH E T_RPATH {$$ = $2;}
+     ;
+
+%%
+
+int main(){
+  yyin = stdin;
+  do{
+	yyparse();
+    
+  }while(!feof(yyin));
+
+  return 0;
+}