#ifndef BIND_STACK_H
#define BIND_STACK_H

#include "containers/mlrval.h"
#include "containers/lhmsmv.h"

// Bound & scoped variables for use in for-loops, function bodies, and
// subroutine bodies.  A frame is 'fenced' if it's at entry to a
// function/subroutine body. Example:
//
// mlr ... put -f '
//   func f(x) {
//     return k;
//   }
//   for (k,v in $*) {
//     $[k] = f(v)
//   }
// '
//
// There is a bind-stack created on entering the put. A frame is pushed in the
// for-loop.  A second frame is pushed in the call to f(x). The former should
// have access to k; the latter should not.

// ----------------------------------------------------------------
// Data private to .c file
typedef struct _bind_stack_frame_t bind_stack_frame_t;

typedef struct _bind_stack_t {
	int num_used;
	int num_allocated;
	bind_stack_frame_t** ppframes;
	bind_stack_frame_t* pbase_frame;
} bind_stack_t;

// ----------------------------------------------------------------
// Constructors/destructors

bind_stack_t* bind_stack_alloc();
void bind_stack_free(bind_stack_t* pstack);

bind_stack_frame_t* bind_stack_frame_alloc_unfenced();
bind_stack_frame_t* bind_stack_frame_alloc_fenced();
void bind_stack_frame_free(bind_stack_frame_t* pframe);

// xxx comment
bind_stack_frame_t* bind_stack_frame_enter(bind_stack_frame_t* pframe);
void bind_stack_frame_exit(bind_stack_frame_t* pframe);

// ----------------------------------------------------------------
// Scope entry/exit

// To be called on entry to scoped block
void bind_stack_push(bind_stack_t* pstack, bind_stack_frame_t* pframe);

// To be called on exit from scoped block.
bind_stack_frame_t* bind_stack_pop(bind_stack_t* pstack);

// ----------------------------------------------------------------
// Access within scope

// Use of local variables on expression right-hand sides
mv_t* bind_stack_resolve(bind_stack_t* pstack, char* key);

// Use of local variables on expression left-hand sides
// The pmv is not copied. You may wish to mv_copy the argument you pass in.
// The pmv will be freed.

// xxx cmt
void bind_stack_define(bind_stack_t* pstack, char* name, mv_t* pmv, char free_flags);
void bind_stack_set(bind_stack_t* pstack, char* name, mv_t* pmv, char free_flags);

// Clears the binding from the top frame without popping it. Useful
// for clearing the baseframe which is never popped.
void bind_stack_clear(bind_stack_t* pstack);

// ----------------------------------------------------------------
// Test/debug

void bind_stack_print(bind_stack_t* pstack);

#endif // BIND_STACK_H