/*
 * symbolsTable.h : Exposed items to manage the symbols table
 * Part of the compiler project for LSD10 language
 * Gaudry Stéphane
 * More information on http://www.gaudry.be/langages-table-des-symboles.html
 * **********************************************************
 */
#ifndef SYMBOLS_TABLE_H
	#define SYMBOLS_TABLE_H
	#include "common.h"
 
	/**
	 * Allows to detect unused variables.
	 */
	typedef enum {
		VAR_USAGE_NEVER,
		VAR_USAGE_SOMETIMES,
		VAR_USAGE_ALWAYS
	}VariableUsage;
 
	/**
	 * Sets usage for a declared variable
	 * @param currentVarNode variable node
	 * @param usage one of the VAR_USAGE_SOMETIMES or VAR_USAGE_ALWAYS values
	 * pre-conditions : currentVarNode is a variable node
	 */
	int setUsage(AstNode *currentVarNode, VariableUsage usage);
 
	/**
	 * @return 1 if the symbols table is available, 0 otherwise
	 */
	int isSymbolsTableAvailable();
 
	/**
	 * Creates a new data storage for the symbols management
	 */
	void initializeSymbolsTable();
 
	/**
	 * Free all resources
	 */
	void finalizeSymbolsTable();
 
	/**
	 * Enters into a new scope
	 */
	void enterScope();
 
	/**
	 * Enters into a new function scope
	 */
	int enterFunctionScope(AstNode* functionNode);
 
	/**
	 * Exits from the current scope, and return to the parent scope if exists
	 */
	void exitScope();
 
	/**
	 * Adds informations about a declaration
	 * All information is given from a declaration node from the AST
	 *
	 * Pre-condition:
	 * 					a createSymbolsTable() call must has been done
	 * 					the finalizeSymbolsTable may not has been called
	 * 					the AST may not has been finalized
	 */
	void addDeclaration(AstNode *declarationNode);
 
	/**
	 * Search into the symbols table for a declaration of a given AST node for the current scope.
	 * If no backward declaration exists, the program exits with an error message
	 *
	 * pre-conditions:
	 * 					currentNode argument may not be NULL
	 * 					currentNode must be an ID or a function call
	 * 					a createSymbolsTable() call must has been done
	 * 					the finalizeSymbolsTable may not has been called
	 * 					the AST may not has been finalized
	 * 					the enterScope() and exitScope() must have been called at the right time to be into the current scope
	 *
	 * returns:			AST declaration node for the current scope
	 */
	AstNode* getDeclaration(AstNode *currentNode);
 
	/**
	 * Returns the memory location of the last declaration, or INITIAL_INT on error
	 */
	int getDeclarationsMemoryUpperBound();
 
	/**
	 * Returns the memory location of the given node declaration, or INITIAL_INT on error
	 */
	int getDeclarationMemoryLocation(AstNode *node);
 
#endif