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[unix-history] / usr / src / usr.bin / indent / parse.c
/*
* Copyright (c) 1980 Regents of the University of California.
* All rights reserved. The Berkeley software License Agreement
* specifies the terms and conditions for redistribution.
*/
#ifndef lint
static char sccsid[] = "@(#)parse.c 5.3 (Berkeley) %G%";
#endif not lint
/*-
*
* Copyright (C) 1976
* by the
* Board of Trustees
* of the
* University of Illinois
*
* All rights reserved
*
*
* FILE NAME:
* parse.c
*
* PURPOSE:
* Contains the routines which keep track of the parse stack.
*
* GLOBALS:
* ps.p_stack = The parse stack, set by both routines
* ps.il = Stack of indentation levels, set by parse
* ps.cstk = Stack of case statement indentation levels, set by parse
* ps.tos = Pointer to top of stack, set by both routines.
*
* FUNCTIONS:
* parse
* reduce
*/\f
/*-
* Copyright (C) 1976 by the Board of Trustees of the University of Illinois
*
* All rights reserved
*
*
* NAME: parse
*
* FUNCTION: Parse is given one input which is a "maxi token" just scanned
* from input. Maxi tokens are signifigant constructs such as else, {,
* do, if (...), etc. Parse works with reduce to maintain a parse stack
* of these constructs. Parse is responsible for the "shift" portion of
* the parse algorithm, and reduce handles the "reduce" portion.
*
* HISTORY: initial coding November 1976 D A Willcox of CAC
*
*/\f
#include "./indent_globs.h";
#include "./indent_codes.h";
parse(tk)
int tk; /* the code for the construct scanned */
{
int i;
#ifdef debug
printf("%2d - %s\n", tk, token);
#endif
while (ps.p_stack[ps.tos] == ifhead && tk != elselit) {
/* true if we have an if without an else */
ps.p_stack[ps.tos] = stmt; /* apply the if(..) stmt ::= stmt
* reduction */
reduce(); /* see if this allows any reduction */
}
switch (tk) { /* go on and figure out what to do with
* the input */
case decl: /* scanned a declaration word */
ps.search_brace = btype_2;
/* indicate that following brace should be on same line */
if (ps.p_stack[ps.tos] != decl) { /* only put one declaration onto
* stack */
break_comma = true; /* while in declaration, newline
* should be forced after comma */
ps.p_stack[++ps.tos] = decl;
ps.il[ps.tos] = ps.i_l_follow;
if (ps.ljust_decl) { /* only do if we want left
* justified declarations */
ps.ind_level = 0;
for (i = ps.tos - 1; i > 0; --i)
if (ps.p_stack[i] == decl)
++ps.ind_level; /* indentation is number
* of declaration levels
* deep we are */
ps.i_l_follow = ps.ind_level;
}
}
break;
case ifstmt: /* scanned if (...) */
if (ps.p_stack[ps.tos] == elsehead && ps.else_if) /* "else if ..." */
ps.i_l_follow = ps.il[ps.tos];
case dolit: /* 'do' */
case forstmt: /* for (...) */
ps.p_stack[++ps.tos] = tk;
ps.il[ps.tos] = ps.ind_level = ps.i_l_follow;
++ps.i_l_follow; /* subsequent statements should be
* indented 1 */
ps.search_brace = btype_2;
break;
case lbrace: /* scanned { */
break_comma = false;/* don't break comma in an initial list */
if (ps.p_stack[ps.tos] == stmt || ps.p_stack[ps.tos] == decl
|| ps.p_stack[ps.tos] == stmtl)
++ps.i_l_follow; /* it is a random, isolated stmt group or
* a declaration */
else {
if (s_code == e_code) {
/* only do this if there is nothing on the line */
--ps.ind_level;
/* it is a group as part of a while, for, etc. */
if (ps.p_stack[ps.tos] == swstmt && ps.case_indent)
--ps.ind_level;
/*
* for a switch, brace should be two levels out from
* the code
*/
}
}
ps.p_stack[++ps.tos] = lbrace;
ps.il[ps.tos] = ps.ind_level;
ps.p_stack[++ps.tos] = stmt;
/* allow null stmt between braces */
ps.il[ps.tos] = ps.i_l_follow;
break;
case whilestmt: /* scanned while (...) */
if (ps.p_stack[ps.tos] == dohead) {
/* it is matched with do stmt */
ps.ind_level = ps.i_l_follow = ps.il[ps.tos];
ps.p_stack[++ps.tos] = whilestmt;
ps.il[ps.tos] = ps.ind_level = ps.i_l_follow;
}
else { /* it is a while loop */
ps.p_stack[++ps.tos] = whilestmt;
ps.il[ps.tos] = ps.i_l_follow;
++ps.i_l_follow;
ps.search_brace = btype_2;
}
break;
case elselit: /* scanned an else */
if (ps.p_stack[ps.tos] != ifhead)
diag(1,"Unmatched 'else'");
else {
ps.ind_level = ps.il[ps.tos]; /* indentation for else should be same as for if */
ps.i_l_follow = ps.ind_level + 1; /* everything following should be in 1 level */
ps.p_stack[ps.tos] = elsehead;
/* remember if with else */
ps.search_brace = btype_2;
}
break;
case rbrace: /* scanned a } */
/* stack should have <lbrace> <stmt> or <lbrace> <stmtl> */
if (ps.p_stack[ps.tos - 1] == lbrace) {
ps.ind_level = ps.i_l_follow = ps.il[--ps.tos];
ps.p_stack[ps.tos] = stmt;
}
else
diag(1,"Stmt nesting error.");
break;
case swstmt: /* had switch (...) */
ps.p_stack[++ps.tos] = swstmt;
ps.cstk[ps.tos] = case_ind;
/* save current case indent level */
ps.il[ps.tos] = ps.i_l_follow;
case_ind = ps.i_l_follow + ps.case_indent; /* cases should be one
* level down from
* switch */
ps.i_l_follow + = ps.case_indent + 1; /* statements should be
* two levels in */
ps.search_brace = btype_2;
break;
case semicolon: /* this indicates a simple stmt */
break_comma = false;/* turn off flag to break after commas in
* a declaration */
ps.p_stack[++ps.tos] = stmt;
ps.il[ps.tos] = ps.ind_level;
break;
default: /* this is an error */
diag(1,"Unknown code to parser");
return;
} /* end of switch */
reduce(); /* see if any reduction can be done */
#ifdef debug
for (i = 1; i <= ps.tos; ++i)
printf("(%d %d)", ps.p_stack[i], ps.il[i]);
printf("\n");
#endif
return;
}
\f/*
* Copyright (C) 1976 by the Board of Trustees of the University of Illinois
*
* All rights reserved
*
*
* NAME: reduce
*
* FUNCTION: Implements the reduce part of the parsing algorithm
*
* ALGORITHM: The following reductions are done. Reductions are repeated
* until no more are possible.
*
* Old TOS New TOS <stmt> <stmt> <stmtl> <stmtl> <stmt> <stmtl> do
* <stmt> "dostmt" if <stmt> "ifstmt" switch <stmt> <stmt>
* decl <stmt> <stmt> "ifelse" <stmt> <stmt> for <stmt> <stmt>
* while <stmt> <stmt> "dostmt" while <stmt>
*
* On each reduction, ps.i_l_follow (the indentation for the following line) is
* set to the indentation level associated with the old TOS.
*
* PARAMETERS: None
*
* RETURNS: Nothing
*
* GLOBALS: ps.cstk ps.i_l_follow = ps.il ps.p_stack = ps.tos =
*
* CALLS: None
*
* CALLED BY: parse \1c
*
* HISTORY: initial coding November 1976 D A Willcox of CAC
*
*/\f
/*----------------------------------------------*\
* | REDUCTION PHASE
\*----------------------------------------------*/
reduce() {
register int i;
for (;;) { /* keep looping until there is nothing
* left to reduce */
switch (ps.p_stack[ps.tos]) {
case stmt:
switch (ps.p_stack[ps.tos - 1]) {
case stmt:
case stmtl:
/* stmtl stmt or stmt stmt */
ps.p_stack[--ps.tos] = stmtl;
break;
case dolit: /* <do> <stmt> */
ps.p_stack[--ps.tos] = dohead;
ps.i_l_follow = ps.il[ps.tos];
break;
case ifstmt:
/* <if> <stmt> */
ps.p_stack[--ps.tos] = ifhead;
for (i = ps.tos - 1;
(
ps.p_stack[i] != stmt
&&
ps.p_stack[i] != stmtl
&&
ps.p_stack[i] != lbrace
);
--i);
ps.i_l_follow = ps.il[i];
/*
* for the time being, we will assume that there
* is no else on this if, and set the indentation
* level accordingly. If an else is scanned, it
* will be fixed up later
*/
break;
case swstmt:
/* <switch> <stmt> */
case_ind = ps.cstk[ps.tos - 1];
case decl: /* finish of a declaration */
case elsehead:
/* <<if> <stmt> else> <stmt> */
case forstmt:
/* <for> <stmt> */
case whilestmt:
/* <while> <stmt> */
ps.p_stack[--ps.tos] = stmt;
ps.i_l_follow = ps.il[ps.tos];
break;
default: /* <anything else> <stmt> */
return;
} /* end of section for <stmt> on top of
* stack */
break;
case whilestmt: /* while (...) on top */
if (ps.p_stack[ps.tos - 1] == dohead) {
/* it is termination of a do while */
ps.p_stack[--ps.tos] = stmt;
break;
}
else
return;
default: /* anything else on top */
return;
}
}
}
Continuous source code history from original PDP-7 UNIX to FreeBSD 2, the first fully unencumbered FreeBSD release.