Add Stack implementation

Author: assalielmehdi

Makefile

@@ -40,16 +40,20 @@ ast:
 
 # Compile files in _03_pc_2_out directory
 
-pc_to_out: pseudo_code_lex pseudo_code interpreter
+pc_to_out: pseudo_code_lex stack pseudo_code interpreter
 	cd ${PC_2_OUT_DIR}; \
-	gcc -o interpreter lex.yy.o interpreter.o pseudo_code.o; \
+	gcc -o interpreter lex.yy.o interpreter.o pseudo_code.o stack.o; \
 	mv interpreter ${TARGET_DIR}/interpreter
 
 pseudo_code_lex:
 	cd ${PC_2_OUT_DIR}; \
 	flex _pseudo_code.lex; \
 	gcc -c lex.yy.c
 
+stack:
+	cd ${PC_2_OUT_DIR}; \
+	gcc -c stack.c
+
 pseudo_code:
 	cd ${PC_2_OUT_DIR}; \
 	gcc -c pseudo_code.c
@@ -62,15 +66,15 @@ interpreter:
 
 clean: clean_in_to_ri clean_pc_to_out
 
-# Compile files in _01_in_2_ri directory
+# Clean _01_in_2_ri directory
 
 clean_in_to_ri:
 	rm ${IN_2_RI_DIR}/lex.yy.c
 	rm ${IN_2_RI_DIR}/*.o
 
 # ---------------------------------------
 
-# Compile files in _03_pc_2_out directory
+# Clean _03_pc_2_out directory
 
 clean_pc_to_out:
 	rm ${PC_2_OUT_DIR}/lex.yy.c

_03_pc_2_out/stack.c

@@ -0,0 +1,25 @@
+#include <stdlib.h>
+#include "stack.h"
+
+_stack _stack_init() {
+  return NULL;
+}
+
+_stack _stack_push(_stack stack, _stack_node_type type, _stack_node_value value) {
+  _stack_node *node = (_stack_node *) malloc(sizeof(_stack_node));
+  node->element.type = type;
+  node->element.value = value;
+  node->next = stack;
+  return node;
+}
+
+_stack _stack_pop(_stack stack) {
+  _stack_node *toFree = stack;
+  stack = stack->next;
+  free(toFree);
+  return stack;
+}
+
+_stack_node_element _stack_peek(_stack stack) {
+  return stack->element;
+}

_03_pc_2_out/stack.h

@@ -0,0 +1,35 @@
+#ifndef STACK_H
+#define STACK_H
+
+typedef enum {
+  STACK_NODE_NUMBER,
+  STACK_NODE_STRING
+} _stack_node_type;
+
+typedef union {
+  char *variable;
+  char *string;
+  double number;
+} _stack_node_value;
+
+typedef struct {
+  _stack_node_type type;
+  _stack_node_value value;
+} _stack_node_element;
+
+typedef struct _stack_node {
+  _stack_node_element element;
+  struct _stack_node *next;
+} _stack_node;
+
+typedef _stack_node *_stack;
+
+_stack _stack_init();
+
+_stack _stack_push(_stack stack, _stack_node_type type, _stack_node_value value);
+
+_stack _stack_pop(_stack stack);
+
+_stack_node_element _stack_peek(_stack stack);
+
+#endif