/* D E F I N I T I O N   M E C H A N I S M */

#include    "parameters.h"
#include	"debug.h"

#include	<alloc.h>
#include	<assert.h>
#include	<em_arith.h>
#include	<em_label.h>

#include	"LLlex.h"
#include	"def.h"
#include	"idf.h"
#include	"main.h"
#include	"misc.h"
#include	"node.h"
#include	"scope.h"
#include	"code.h"
#include	"type.h"
#include	"lookup.h"
#include	"error.h"

struct def *MkDef(register struct idf *id, register struct scope *scope,
		long kind)
{
	/*	Create a new definition structure in scope "scope", with
	 *	id "id" and kind "kind".
	 */
	register struct def *df = new_def();

	df->df_idf = id;
	df->df_scope = scope;
	df->df_kind = kind;
	df->df_type = error_type;
	df->df_next = id->id_def;
	id->id_def = df;

	/* enter the definition in the list of definitions in this scope
	 */
	df->df_nextinscope = scope->sc_def;
	scope->sc_def = df;
	return df;
}

struct def *define(register struct idf *id, register struct scope *scope,
		long kind)
{
	/*	Declare an identifier in a scope, but first check if it
	 already has been defined.
	 If so, then check for the cases in which this is legal,
	 and otherwise give an error message.
	 */
	register struct def *df;

	if ( (df = lookup(id, scope, 0L)) )
	{
		if (df->df_kind == D_INUSE)
		{
			if (kind != D_INUSE)
			{
				error("\"%s\" already used in this block", id->id_text);
			}
			return MkDef(id, scope, kind);
		}
		if (df->df_kind == D_ERROR)
		{
			/* used in forward references */
			df->df_kind = kind;
			return df;
		}
		/* other cases fit in an int (assume at least 2 bytes) */
		switch ((int) df->df_kind)
		{

		case D_LABEL:
			/* generate error message somewhere else */
			return NULLDEF;

		case D_PARAMETER:
			if (kind == D_VARIABLE)
				/* program parameter declared as variable */
				return df;
			break;

		case D_FORWTYPE:
			if (kind == D_FORWTYPE)
				return df;
			if (kind == D_TYPE)
			{
				/* forward reference resolved */
				df->df_kind = D_FTYPE;
				return df;
			}
			else
				error("identifier \"%s\" must be a type", id->id_text);
			return NULLDEF;

		case D_FWPROCEDURE:
			if (kind == D_PROCEDURE)
				return df;
			error("procedure identification \"%s\" expected", id->id_text);
			return NULLDEF;

		case D_FWFUNCTION:
			if (kind == D_FUNCTION)
				return df;
			error("function identification \"%s\" expected", id->id_text);
			return NULLDEF;

		}
		if (kind != D_ERROR)
			/* avoid spurious error messages */
			error("identifier \"%s\" already declared", id->id_text);

		return NULLDEF;
	}

	return MkDef(id, scope, kind);
}

void DoDirective(struct idf *directive, struct node *nd, struct type *tp,
		struct scopelist *scl, int function)
{
	long kind; /* kind of directive */
	int inp; /* internal or external name */
	int ext = 0; /* directive = EXTERN */
	struct def *df = lookup(directive, PervasiveScope, D_INUSE);

	if (!df)
	{
		if (!is_anon_idf(directive))
			node_error(nd, "\"%s\" unknown directive", directive->id_text);
		return;
	}

	if (df->df_kind == D_FORWARD)
	{
		kind = function ? D_FWFUNCTION : D_FWPROCEDURE;
		inp = (proclevel > 1);
	}
	else if (df->df_kind == D_EXTERN)
	{
		kind = function ? D_FUNCTION : D_PROCEDURE;
		inp = 0;
		ext = 1;
	}
	else
	{
		node_error(nd, "\"%s\" unknown directive", directive->id_text);
		return;
	}

	if ( (df = define(nd->nd_IDF, CurrentScope, kind)) )
	{
		if (df->df_kind != kind)
		{
			/* identifier already forward declared */
			node_error(nd, "\"%s\" already forward declared",
					nd->nd_IDF->id_text);
			return;
		}

		df->df_type = tp;
		df->prc_vis = scl;
		df->prc_name = gen_proc_name(nd->nd_IDF, inp);
		if (ext)
		{
			if (!(df->df_flags & D_EXTERNAL) && proclevel > 1)
				tp->prc_nbpar -= pointer_size;
			/* was added for static link which is not needed now.
			 But make sure this is done only once (look at the
			 D_EXTERNAL flag).
			 */
			df->df_flags |= D_EXTERNAL;
		}
		df->df_flags |= D_SET;
	}
}

struct def *DeclProc(register struct node *nd, struct type *tp,
		register struct scopelist *scl)
{
	register struct def *df;

	if ( (df = define(nd->nd_IDF, CurrentScope, D_PROCEDURE)) )
	{
		df->df_flags |= D_SET;
		if (df->df_kind == D_FWPROCEDURE)
		{
			df->df_kind = D_PROCEDURE; /* identification */

			/* Simulate a call to open_scope(), which has already
			 * been performed in the forward declaration.
			 */
			CurrVis = df->prc_vis;

			if (tp->prc_params)
				node_error(nd, "\"%s\" already declared", nd->nd_IDF->id_text);
		}
		else
		{ /* normal declaration */
			df->df_type = tp;
			df->prc_name = gen_proc_name(nd->nd_IDF, (proclevel > 1));
			/* simulate open_scope() */
			CurrVis = df->prc_vis = scl;
		}
		routine_label(df);
	}
	else
		CurrVis = scl; /* simulate open_scope() */

	return df;
}

struct def *
DeclFunc(register struct node *nd, struct type *tp,
		register struct scopelist *scl)
{
	register struct def *df;

	if ( (df = define(nd->nd_IDF, CurrentScope, D_FUNCTION)) )
	{
		df->df_flags &= ~D_SET;
		if (df->df_kind == D_FUNCTION)
		{ /* declaration */
			if (!tp)
			{
				node_error(nd, "\"%s\" illegal function declaration",
						nd->nd_IDF->id_text);
				tp = construct_type(T_FUNCTION, error_type);
			}
			/* simulate open_scope() */
			CurrVis = df->prc_vis = scl;
			df->df_type = tp;
			df->prc_name = gen_proc_name(nd->nd_IDF, (proclevel > 1));
		}
		else
		{ /* identification */
			assert(df->df_kind == D_FWFUNCTION);

			df->df_kind = D_FUNCTION;
			CurrVis = df->prc_vis;

			if (tp)
				node_error(nd, "\"%s\" already declared", nd->nd_IDF->id_text);

		}
		routine_label(df);
	}
	else
		CurrVis = scl; /* simulate open_scope() */

	return df;
}

void EndFunc(register struct def *df)
{
	/* assignment to functionname is illegal outside the functionblock */
	df->prc_res = 0;

	/* Give the error about assignment as soon as possible. The
	 * |= assignment inhibits a warning in the main procedure.
	 */
	if (!(df->df_flags & D_SET))
	{
		error("function \"%s\" not assigned", df->df_idf->id_text);
		df->df_flags |= D_SET;
	}
}

void EndBlock(register struct def *block_df)
{
	register struct def *tmp_def = CurrentScope->sc_def;
	register struct def *df;

	while (tmp_def)
	{
		df = tmp_def;
		/* The length of a usd_def chain is at most 1.
		 * The while is just defensive programming.
		 */
		while (df->df_kind & D_INUSE)
			df = df->usd_def;

		if (!is_anon_idf(df->df_idf) && (df->df_scope == CurrentScope))
		{
			if (!(df->df_kind & (D_ENUM | D_LABEL | D_ERROR)))
			{
				if (!(df->df_flags & D_USED))
				{
					if (!(df->df_flags & D_SET))
					{
						warning("\"%s\" neither set nor used in \"%s\"",
								df->df_idf->id_text, block_df->df_idf->id_text);
					}
					else
					{
						warning("\"%s\" unused in \"%s\"", df->df_idf->id_text,
								block_df->df_idf->id_text);
					}
				}
				else if (!(df->df_flags & D_SET))
				{
					if (!(df->df_flags & D_LOOPVAR))
						warning("\"%s\" not set in \"%s\"", df->df_idf->id_text,
								block_df->df_idf->id_text);
				}
			}

		}
		tmp_def = tmp_def->df_nextinscope;
	}
}
