--- /dev/null
+static char sccsid[] = "@(#)parse.c 4.1 (Berkeley) %G%";
+
+/*
+
+ 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:
+ p_stack = The parse stack, set by both routines
+ il = Stack of indentation levels, set by parse
+ cstk = Stack of case statement indentation levels, set by parse
+ 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.
+
+ALGORITHM:
+ 1) If there is "ifstmt" on the stack and input is anything other than
+ an else, then change the top of stack (TOS) to <stmt>. Do a reduce.
+ 2) Use a switch statement to implement the following shift operations:
+
+ TOS\b\b\b___ Input\b\b\b\b\b_____ Stack\b\b\b\b\b_____ Note\b\b\b\b____
+ decl decl nothing
+ anything else decl decl
+ "dostmt" while (..) Change TOS to <stmt>
+ anything else while (..) while
+ "ifstmt" else Change TOS to "ifelse"
+ { <stmtl> } Change { <stmtl>
+ to <stmtl>
+ switch (..) switch
+ do do
+ for(..) for
+ ; <stmt>
+ { { <stmt>
+
+PARAMETERS:
+ tk An integer code for the maxi token scanned
+
+RETURNS:
+ Nothing
+
+GLOBALS:
+ break_comma = Set to true when in a declaration but not initialization
+ btype_2
+ case_ind =
+ cstk =
+ i_l_follow =
+ il = Stack of indentation levels
+ ind_level =
+ p_stack = Stack of token codes
+ search_brace = Set to true if we must look for possibility of moving a
+ brace
+ tos = Pointer to top of p_stack, il, and cstk
+
+CALLS:
+ printf (lib)
+ reduce
+
+CALLED BY:
+ main
+
+HISTORY:
+ initial coding November 1976 D A Willcox of CAC
+
+*/\f
+
+#include "./indent_globs.h";
+#include "./indent_codes.h";
+
+
+int p_stack[50] = stmt;
+ /* this is the parser's stack */
+int il[50]; /* this stack stores indentation levels */
+int cstk[50]; /* used to store case stmt indentation levels */
+int tos = 0; /* pointer to top of stack */
+
+
+parse (tk)
+int tk; /* the code for the construct scanned */
+{
+ int i;
+
+#ifdef debug
+ printf ("%2d - %s\n", tk, token);
+#endif
+ while (p_stack[tos] == ifhead && tk != elselit) {
+ /* true if we have an if without an else */
+ p_stack[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 */
+ search_brace = btype_2;
+ /* indicate that following brace should be on same line */
+ if (p_stack[tos] != decl) {
+ /* only put one declaration onto stack */
+ break_comma = true;
+ /* while in declaration, newline should be forced after comma */
+ p_stack[++tos] = decl;
+ il[tos] = i_l_follow;
+
+ if (ljust_decl) {
+ /* only do if we want left justified declarations */
+ ind_level = 0;
+ for (i = tos - 1; i > 0; --i)
+ if (p_stack[i] == decl)
+ ++ind_level;
+ /* indentation is number of declaration levels deep we are */
+ i_l_follow = ind_level;
+ }
+ }
+ break;
+
+ case ifstmt: /* scanned if (...) */
+ case dolit: /* 'do' */
+ case forstmt: /* for (...) */
+ p_stack[++tos] = tk;
+ il[tos] = ind_level = i_l_follow;
+ ++i_l_follow; /* subsequent statements should be indented 1 */
+ search_brace = btype_2;
+ break;
+
+ case lbrace: /* scanned { */
+ break_comma = false;
+ /* don't break comma in an initial list */
+ if (p_stack[tos] == stmt || p_stack[tos] == decl
+ || p_stack[tos] == stmtl)
+ ++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 */
+ --ind_level;
+ /* it is a group as part of a while, for, etc. */
+ if (p_stack[tos] == swstmt)
+ --ind_level;
+ /* for a switch, brace should be two levels out from the code
+ */
+ }
+ }
+
+ p_stack[++tos] = lbrace;
+ il[tos] = ind_level;
+ p_stack[++tos] = stmt;
+ /* allow null stmt between braces */
+ il[tos] = i_l_follow;
+ break;
+
+ case whilestmt: /* scanned while (...) */
+ if (p_stack[tos] == dohead) {
+ /* it is matched with do stmt */
+ ind_level = i_l_follow = il[tos];
+ p_stack[++tos] = whilestmt;
+ il[tos] = ind_level = i_l_follow;
+ }
+ else { /* it is a while loop */
+ p_stack[++tos] = whilestmt;
+ il[tos] = i_l_follow;
+ ++i_l_follow;
+ search_brace = btype_2;
+ }
+
+ break;
+
+ case elselit: /* scanned an else */
+
+ if (p_stack[tos] != ifhead) {
+ printf ("%d: Unmatched else\n", line_no);
+ }
+ else {
+ ind_level = il[tos];
+ /* indentation for else should be same as for if */
+ i_l_follow = ind_level + 1;
+ /* everything following should be in 1 level */
+ p_stack[tos] = elsehead;
+ /* remember if with else */
+ search_brace = btype_2;
+ }
+
+ break;
+
+ case rbrace: /* scanned a } */
+ /* stack should have <lbrace> <stmt> or <lbrace> <stmtl> */
+ if (p_stack[tos - 1] == lbrace) {
+ ind_level = i_l_follow = il[--tos];
+ p_stack[tos] = stmt;
+ }
+ else {
+ printf ("%d: Stmt nesting error\n", line_no);
+ }
+
+ break;
+
+ case swstmt: /* had switch (...) */
+ p_stack[++tos] = swstmt;
+ cstk[tos] = case_ind;
+ /* save current case indent level */
+ il[tos] = i_l_follow;
+ case_ind = i_l_follow + 1;
+ /* cases should be one level down from switch */
+ i_l_follow + = 2; /* statements should be two levels in */
+ 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 */
+ p_stack[++tos] = stmt;
+ il[tos] = ind_level;
+ break;
+
+ default: /* this is an error */
+ printf ("%d: Unknown code to parser - %d\n", line_no, tk);
+ return;
+
+
+ } /* end of switch */
+
+ reduce (); /* see if any reduction can be done */
+#ifdef debug
+ for (i = 1; i <= tos; ++i)
+ printf ("(%d %d)", p_stack[i], 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\b\b\b___ TOS\b\b\b___ New\b\b\b___ TOS\b\b\b___
+ <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, 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:
+ cstk
+ i_l_follow =
+ il
+ p_stack =
+ tos =
+
+CALLS:
+ None
+
+CALLED BY:
+ parse
+\1c
+HISTORY:
+ initial coding November 1976 D A Willcox of CAC
+
+*/\f
+/*----------------------------------------------*\
+| REDUCTION PHASE
+\*----------------------------------------------*/
+reduce () {
+
+ register int i;
+ /* local looping variable */
+
+ for (;;) { /* keep looping until there is nothing left to
+ reduce */
+
+ switch (p_stack[tos]) {
+
+ case stmt:
+ switch (p_stack[tos - 1]) {
+
+ case stmt:
+ case stmtl:
+ /* stmtl stmt or stmt stmt */
+ p_stack[--tos] = stmtl;
+ break;
+
+ case dolit:
+ /* <do> <stmt> */
+ p_stack[--tos] = dohead;
+ i_l_follow = il[tos];
+ break;
+
+ case ifstmt:
+ /* <if> <stmt> */
+ p_stack[--tos] = ifhead;
+ for (i = tos - 1;
+ (
+ p_stack[i] != stmt
+ &&
+ p_stack[i] != stmtl
+ &&
+ p_stack[i] != lbrace
+ );
+ --i);
+ i_l_follow = 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 = cstk[tos - 1];
+
+ case decl: /* finish of a declaration */
+ case elsehead:
+ /* <<if> <stmt> else> <stmt> */
+ case forstmt:
+ /* <for> <stmt> */
+ case whilestmt:
+ /* <while> <stmt> */
+ p_stack[--tos] = stmt;
+ i_l_follow = il[tos];
+ break;
+
+ default: /* <anything else> <stmt> */
+ return;
+
+ } /* end of section for <stmt> on top of stack */
+ break;
+
+ case whilestmt: /* while (...) on top */
+ if (p_stack[tos - 1] == dohead) {
+ /* it is termination of a do while */
+ p_stack[--tos] = stmt;
+ break;
+ }
+ else
+ return;
+
+ default: /* anything else on top */
+ return;
+
+ } /* end of big switch */
+
+ } /* end of reduction phase for (;;) */
+}
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