#ifndef NCTREF_VARTABLE_H
#define NCTREF_VARTABLE_H

#include"types.h"

typedef enum {
	VARTABLEENTRY_SYMBOL, VARTABLEENTRY_TYPE, VARTABLEENTRY_VAR
} VarTableEntryKind;

union AST;
typedef struct UseDef {
	union AST *def; // assign stmt
	union AST *use; // corresponding AST_EXPR_VAR
	union AST *stmt; // whole using stmt
	struct UseDef *next;
} UseDef;

// Stack, necessary for "possible reaching defs" such as from if statements
typedef struct ReachingDefs {
	size_t defCount;
	union AST **defs;
	
	struct ReachingDefs *parent;
} ReachingDefs;
struct ReachingDefs *reachingdefs_push(struct ReachingDefs*);
struct ReachingDefs *reachingdefs_coalesce(struct ReachingDefs*);
void reachingdefs_set(struct ReachingDefs*, union AST*);

typedef struct VarTableEntry {
	Type *type;
	
	VarTableEntryKind kind;
	struct {
		union {
			struct {
				char isLocal;
				char isExternal;
				const char *name;
			} symbol;
			struct {
				// For debugging
				
				const char *name;
				
				// Register allocation
				
				// vars in loops have higher priority
				// a more advanced approach would be to use weights for different colors (e.g. vars for mul "should" be in eax)
				uint8_t priority;
				uint16_t color, degree;
				
				// Used during parsing
				
				ReachingDefs *reachingDefs;
				
				// Optimizations
				
				UseDef *usedefFirst;
				UseDef *usedefLast;
			} var;
		};
	} data;
} VarTableEntry;

typedef struct VarTable {
	struct VarTable *parent;
	
	size_t count;
	const char **names;
	VarTableEntry **data;
} VarTable;

VarTable *vartable_new(VarTable*);
VarTableEntry *vartable_get(VarTable*, const char*);
VarTableEntry *vartable_find(VarTable*, const char*);
VarTableEntry *vartable_set(VarTable*, const char*, VarTableEntry*);

void vartable_new_reachingdefs_for_all_vars(VarTable*);
void vartable_coalesce_reachingdefs_for_all_vars(VarTable*);

#endif