check.c

<B>Digital的Unix操作系统VAX 4.2源码</B>

/*#@(#)check.c	4.1	Ultrix	7/17/90*/
/* Copyright (c) 1982 Regents of the University of California */

static char sccsid[] = "@(#)check.c 1.5 8/10/83";

static char rcsid[] = "$Header: check.c,v 1.3 84/03/27 10:19:54 linton Exp $";

/*
 * Check a tree for semantic correctness.
 */

#include "defs.h"
#include "tree.h"
#include "operators.h"
#include "events.h"
#include "symbols.h"
#include "scanner.h"
#include "source.h"
#include "object.h"
#include "mappings.h"
#include "process.h"

#ifndef public
#endif

/*
 * Check that the nodes in a tree have the correct arguments
 * in order to be evaluated.  Basically the error checking here
 * frees the evaluation routines from worrying about anything
 * except dynamic errors, e.g. subscript out of range.
 */

public check(p)
register Node p;
{
    Address addr;
    Symbol f;

    checkref(p);
    switch (p->op) {
	case O_LIST:
	    if (p->value.arg[0]->op == O_SYM) {
		f = p->value.arg[0]->value.sym;
		if (not isblock(f) or ismodule(f)) {
		    error("\"%s\" is not a procedure or function", symname(f));
		}
		addr = firstline(f);
		if (addr == NOADDR) {
		    error("\"%s\" is empty", symname(f));
		}
	    }
	    break;

	case O_TRACE:
	case O_TRACEI:
	    chktrace(p);
	    break;

	case O_STOP:
	case O_STOPI:
	    chkstop(p);
	    break;

	case O_CALL:
	    if (not isroutine(p->value.arg[0]->nodetype)) {
		beginerrmsg();
		fprintf(stderr, "\"");
		prtree(stderr, p->value.arg[0]);
		fprintf(stderr, "\" not call-able");
		enderrmsg();
	    }
	    break;

	default:
	    break;
    }
}

/*
 * Check arguments to a trace command.
 */

private chktrace(p)
Node p;
{
    Node exp, place, cond;

    exp = p->value.arg[0];
    place = p->value.arg[1];
    cond = p->value.arg[2];
    if (exp == nil) {
	chkblock(place);
    } else if (exp->op == O_LCON or exp->op == O_QLINE) {
	if (place != nil) {
	    error("unexpected \"at\" or \"in\"");
	}
	if (p->op == O_TRACE) {
	    chkline(exp);
	} else {
	    chkaddr(exp);
	}
    } else if (place != nil and (place->op == O_QLINE or place->op == O_LCON)) {
	if (p->op == O_TRACE) {
	    chkline(place);
	} else {
	    chkaddr(place);
	}
    } else {
	if (exp->op != O_RVAL and exp->op != O_SYM and exp->op != O_CALL) {
	    error("can't trace expressions");
	}
	chkblock(place);
    }
}

/*
 * Check arguments to a stop command.
 */

private chkstop(p)
Node p;
{
    Node exp, place, cond;

    exp = p->value.arg[0];
    place = p->value.arg[1];
    cond = p->value.arg[2];
    if (exp != nil) {
	if (exp->op != O_RVAL and exp->op != O_SYM and exp->op != O_LCON) {
	    beginerrmsg();
	    fprintf(stderr, "expected variable, found ");
	    prtree(stderr, exp);
	    enderrmsg();
	}
	chkblock(place);
    } else if (place != nil) {
	if (place->op == O_SYM) {
	    chkblock(place);
	} else {
	    if (p->op == O_STOP) {
		chkline(place);
	    } else {
		chkaddr(place);
	    }
	}
    }
}

/*
 * Check to see that the given node specifies some subprogram.
 * Nil is ok since that means the entire program.
 */

private chkblock(b)
Node b;
{
    Symbol p, outer;

    if (b != nil) {
	if (b->op != O_SYM) {
	    beginerrmsg();
	    fprintf(stderr, "expected subprogram, found ");
	    prtree(stderr, b);
	    enderrmsg();
	} else if (ismodule(b->value.sym)) {
	    outer = b->value.sym;
	    while (outer != nil) {
		find(p, outer->name) where p->block == outer endfind(p);
		if (p == nil) {
		    outer = nil;
		    error("\"%s\" is not a subprogram", symname(b->value.sym));
		} else if (ismodule(p)) {
		    outer = p;
		} else {
		    outer = nil;
		    b->value.sym = p;
		}
	    }
	} else if (not isblock(b->value.sym)) {
	    error("\"%s\" is not a subprogram", symname(b->value.sym));
	}
    }
}

/*
 * Check to make sure a node corresponds to a source line.
 */

private chkline(p)
Node p;
{
    if (p == nil) {
	error("missing line");
    } else if (p->op != O_QLINE and p->op != O_LCON) {
	error("expected source line number, found \"%t\"", p);
    }
}

/*
 * Check to make sure a node corresponds to an address.
 */

private chkaddr(p)
Node p;
{
    if (p == nil) {
	error("missing address");
    } else if (p->op != O_LCON and p->op != O_QLINE) {
	beginerrmsg();
	fprintf(stderr, "expected address, found \"");
	prtree(stderr, p);
	fprintf(stderr, "\"");
	enderrmsg();
    }
}