grammar.y

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/*************************************************************************
 * Copyright (c) 2011 AT&T Intellectual Property 
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * https://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors: Details at https://graphviz.org
 *************************************************************************/
 
%require "3.0"
 
  /* By default, Bison emits a parser using symbols prefixed with "yy". Graphviz
   * contains multiple Bison-generated parsers, so we alter this prefix to avoid
   * symbol clashes.
   */
%define api.prefix {aag}
 
%{
 
#include <stdbool.h>
#include <stdio.h>
#include <cghdr.h>
#include <cgraph/agxbuf.h>
#include <cgraph/alloc.h>
#include <cgraph/streq.h>
#include <cgraph/unreachable.h>
#include <stddef.h>
extern void aagerror(const char*);
 
static const char Key[] = "key";
static int SubgraphDepth = 0;
 
typedef union s {                                       /* possible items in generic list */
                Agnode_t                *n;
                Agraph_t                *subg;
                Agedge_t                *e;
                Agsym_t                 *asym;  /* bound attribute */
                char                    *name;  /* unbound attribute */
                struct item_s   *list;  /* list-of-lists (for edgestmt) */
} val_t;
 
typedef struct item_s {         /* generic list */
        int                             tag;    /* T_node, T_subgraph, T_edge, T_attr */
        val_t                   u;              /* primary element */
        char                    *str;   /* secondary value - port or attr value */
        struct item_s   *next;
} item;
 
typedef struct list_s {         /* maintain head and tail ptrs for fast append */
        item                    *first;
        item                    *last;
} list_t;
 
typedef struct gstack_s {
        Agraph_t *g;
        Agraph_t *subg;
        list_t  nodelist,edgelist,attrlist;
        struct gstack_s *down;
} gstack_t;
 
/* functions */
static void appendnode(char *name, char *port, char *sport);
static void attrstmt(int tkind, char *macroname);
static void startgraph(char *name, bool directed, bool strict);
static void getedgeitems(void);
static void newedge(Agnode_t *t, char *tport, Agnode_t *h, char *hport, char *key);
static void edgerhs(Agnode_t *n, char *tport, item *hlist, char *key);
static void appendattr(char *name, char *value);
static void bindattrs(int kind);
static void applyattrs(void *obj);
static void endgraph(void);
static void endnode(void);
static void endedge(void);
static void freestack(void);
static char* concat(char*, char*);
static char* concatPort(char*, char*);
 
static void opensubg(char *name);
static void closesubg(void);
 
/* global */
static Agraph_t *G;                             /* top level graph */
static  Agdisc_t        *Disc;          /* discipline passed to agread or agconcat */
static gstack_t *S;
 
%}
 
%union  {
                        int                             i;
                        char                    *str;
                        struct Agnode_s *n;
}
 
%token <i> T_graph T_node T_edge T_digraph T_subgraph T_strict T_edgeop
        /* T_list, T_attr are internal tags, not really tokens */
%token T_list T_attr
%token <str> T_atom T_qatom
 
%type <i>  optstrict graphtype rcompound attrtype
%type <str> optsubghdr optgraphname optmacroname atom qatom
 
 
%%
 
graph           :  hdr body {freestack(); endgraph();}
                        |  error        {if (G) {freestack(); endgraph(); agclose(G); G = Ag_G_global = NULL;}}
                        |  /* empty */
                        ;
 
body            : '{' optstmtlist '}' ;
 
hdr                     :       optstrict graphtype optgraphname {startgraph($3,$2 != 0,$1 != 0);}
                        ;
 
optgraphname:   atom {$$=$1;} | /* empty */ {$$=0;} ;
 
optstrict       :  T_strict  {$$=1;} |  /* empty */ {$$=0;} ;
 
graphtype       :       T_graph {$$ = 0;} |     T_digraph {$$ = 1;} ;
 
optstmtlist     :       stmtlist |      /* empty */ ;
 
stmtlist        :       stmtlist stmt | stmt ;
 
optsemi         : ';' | ;
 
stmt            :  attrstmt  optsemi
                        |  compound      optsemi
                        ;
 
compound        :       simple rcompound optattr
                                        {if ($2) endedge(); else endnode();}
                        ;
 
simple          :       nodelist | subgraph ;
 
rcompound       :       T_edgeop {getedgeitems();} simple {getedgeitems();} rcompound {$$ = 1;}
                        |       /* empty */ {$$ = 0;}
                        ;
 
 
nodelist        : node | nodelist ',' node ;
 
node            : atom {appendnode($1,NULL,NULL);}
            | atom ':' atom {appendnode($1,$3,NULL);}
            | atom ':' atom ':' atom {appendnode($1,$3,$5);}
            ;
 
attrstmt        :  attrtype optmacroname attrlist {attrstmt($1,$2);}
                        |  graphattrdefs {attrstmt(T_graph,NULL);}
                        ;
 
attrtype :      T_graph {$$ = T_graph;}
                        | T_node {$$ = T_node;}
                        | T_edge {$$ = T_edge;}
                        ;
 
optmacroname : atom '=' {$$ = $1;}
                        | /* empty */ {$$ = NULL; }
                        ;
 
optattr         :       attrlist |  /* empty */ ;
 
attrlist        : optattr '[' optattrdefs ']' ;
 
optattrdefs     : optattrdefs attrdefs 
                        | /* empty */ ;
 
attrdefs        :  attrassignment optseparator
                        ;
 
attrassignment  :  atom '=' atom {appendattr($1,$3);}
                        ;
 
graphattrdefs : attrassignment
                        ;
 
subgraph        :  optsubghdr {opensubg($1);} body {closesubg();}
                        ;
 
optsubghdr      : T_subgraph atom {$$=$2;}
                        | T_subgraph  {$$=NULL;}
                        | /* empty */ {$$=NULL;}
                        ;
 
optseparator :  ';' | ',' | /*empty*/ ;
 
atom    :  T_atom {$$ = $1;}
                        |  qatom {$$ = $1;}
                        ;
 
qatom   :  T_qatom {$$ = $1;}
                        |  qatom '+' T_qatom {$$ = concat($1,$3);}
                        ;
%%
 
static item *newitem(int tag, void *p0, char *p1)
{
        item    *rv = agalloc(G,sizeof(item));
        rv->tag = tag; rv->u.name = (char*)p0; rv->str = p1;
        return rv;
}
 
static item *cons_node(Agnode_t *n, char *port)
        { return newitem(T_node,n,port); }
 
static item *cons_attr(char *name, char *value)
        { return newitem(T_atom,name,value); }
 
static item *cons_list(item *list)
        { return newitem(T_list,list,NULL); }
 
static item *cons_subg(Agraph_t *subg)
        { return newitem(T_subgraph,subg,NULL); }
 
static gstack_t *push(gstack_t *s, Agraph_t *subg) {
        gstack_t *rv;
        rv = agalloc(G,sizeof(gstack_t));
        rv->down = s;
        rv->g = subg;
        return rv;
}
 
static gstack_t *pop(gstack_t *s)
{
        gstack_t *rv;
        rv = s->down;
        agfree(G,s);
        return rv;
}
 
static void delete_items(item *ilist)
{
        item    *p,*pn;
 
        for (p = ilist; p; p = pn) {
                pn = p->next;
                if (p->tag == T_list) delete_items(p->u.list);
                if (p->tag == T_atom) agstrfree(G,p->str);
                agfree(G,p);
        }
}
 
static void deletelist(list_t *list)
{
        delete_items(list->first);
        list->first = list->last = NULL;
}
 
static void listapp(list_t *list, item *v)
{
        if (list->last) list->last->next = v;
        list->last = v;
        if (list->first == NULL) list->first = v;
}
 
 
/* attrs */
static void appendattr(char *name, char *value)
{
        item            *v;
 
        assert(value != NULL);
        v = cons_attr(name,value);
        listapp(&(S->attrlist),v);
}
 
static void bindattrs(int kind)
{
        item            *aptr;
        char            *name;
 
        for (aptr = S->attrlist.first; aptr; aptr = aptr->next) {
                assert(aptr->tag == T_atom);    /* signifies unbound attr */
                name = aptr->u.name;
                if (kind == AGEDGE && streq(name,Key)) continue;
                if ((aptr->u.asym = agattr(S->g,kind,name,NULL)) == NULL)
                        aptr->u.asym = agattr(S->g,kind,name,"");
                aptr->tag = T_attr;                             /* signifies bound attr */
                agstrfree(G,name);
        }
}
 
/* attach node/edge specific attributes */
static void applyattrs(void *obj)
{
        item            *aptr;
 
        for (aptr = S->attrlist.first; aptr; aptr = aptr->next) {
                if (aptr->tag == T_attr) {
                        if (aptr->u.asym) {
                                agxset(obj,aptr->u.asym,aptr->str);
                        }
                }
                else {
                        assert(AGTYPE(obj) == AGINEDGE || AGTYPE(obj) == AGOUTEDGE);
                        assert(aptr->tag == T_atom);
                        assert(streq(aptr->u.name,Key));
                }
        }
}
 
static void nomacros(void)
{
  agwarningf("attribute macros not implemented");
}
 
/* attrstmt:
 * First argument is always attrtype, so switch covers all cases.
 * This function is used to handle default attribute value assignment.
 */
static void attrstmt(int tkind, char *macroname)
{
        item                    *aptr;
        int                             kind = 0;
        Agsym_t*  sym;
 
                /* creating a macro def */
        if (macroname) nomacros();
                /* invoking a macro def */
        for (aptr = S->attrlist.first; aptr; aptr = aptr->next)
                if (aptr->str == NULL) nomacros();
 
        switch(tkind) {
                case T_graph: kind = AGRAPH; break;
                case T_node: kind = AGNODE; break;
                case T_edge: kind = AGEDGE; break;
                default: UNREACHABLE();
        }
        bindattrs(kind);        /* set up defaults for new attributes */
        for (aptr = S->attrlist.first; aptr; aptr = aptr->next) {
                /* If the tag is still T_atom, aptr->u.asym has not been set */
                if (aptr->tag == T_atom) continue;
                if (!(aptr->u.asym->fixed) || (S->g != G))
                        sym = agattr(S->g,kind,aptr->u.asym->name,aptr->str);
                else
                        sym = aptr->u.asym;
                if (S->g == G)
                        sym->print = true;
        }
        deletelist(&(S->attrlist));
}
 
/* nodes */
 
static void appendnode(char *name, char *port, char *sport)
{
        item            *elt;
 
        if (sport) {
                port = concatPort (port, sport);
        }
        elt = cons_node(agnode(S->g, name, 1), port);
        listapp(&(S->nodelist),elt);
        agstrfree(G,name);
}
 
/* apply current optional attrs to nodelist and clean up lists */
/* what's bad is that this could also be endsubg.  also, you can't
clean up S->subg in closesubg() because S->subg might be needed
to construct edges.  these are the sort of notes you write to yourself
in the future. */
static void endnode(void)
{
        item    *ptr;
 
        bindattrs(AGNODE);
        for (ptr = S->nodelist.first; ptr; ptr = ptr->next)
                applyattrs(ptr->u.n);
        deletelist(&(S->nodelist));
        deletelist(&(S->attrlist));
        deletelist(&(S->edgelist));
        S->subg = 0;  /* notice a pattern here? :-( */
}
 
/* edges - store up node/subg lists until optional edge key can be seen */
 
static void getedgeitems(void)
{
        item    *v = 0;
 
        if (S->nodelist.first) {
                v = cons_list(S->nodelist.first);
                S->nodelist.first = S->nodelist.last = NULL;
        }
        else {if (S->subg) v = cons_subg(S->subg); S->subg = 0;}
        /* else nil append */
        if (v) listapp(&(S->edgelist),v);
}
 
static void endedge(void)
{
        char                    *key;
        item                    *aptr,*tptr,*p;
 
        Agnode_t                *t;
        Agraph_t                *subg;
 
        bindattrs(AGEDGE);
 
        /* look for "key" pseudo-attribute */
        key = NULL;
        for (aptr = S->attrlist.first; aptr; aptr = aptr->next) {
                if ((aptr->tag == T_atom) && streq(aptr->u.name,Key))
                        key = aptr->str;
        }
 
        /* can make edges with node lists or subgraphs */
        for (p = S->edgelist.first; p->next; p = p->next) {
                if (p->tag == T_subgraph) {
                        subg = p->u.subg;
                        for (t = agfstnode(subg); t; t = agnxtnode(subg,t))
                                edgerhs(agsubnode(S->g, t, 0), NULL, p->next, key);
                }
                else {
                        for (tptr = p->u.list; tptr; tptr = tptr->next)
                                edgerhs(tptr->u.n,tptr->str,p->next,key);
                }
        }
        deletelist(&(S->nodelist));
        deletelist(&(S->edgelist));
        deletelist(&(S->attrlist));
        S->subg = 0;
}
 
/* concat:
 */
static char*
concat (char* s1, char* s2)
{
  char*  s;
  char   buf[BUFSIZ];
  char*  sym;
  size_t len = strlen(s1) + strlen(s2) + 1;
 
  if (len <= BUFSIZ) sym = buf;
  else sym = gv_alloc(len);
  strcpy(sym,s1);
  strcat(sym,s2);
  s = agstrdup (G,sym);
  agstrfree (G,s1);
  agstrfree (G,s2);
  if (sym != buf) free (sym);
  return s;
}
 
static char*
concatPort (char* s1, char* s2)
{
  agxbuf buf = {0};
 
  agxbprint(&buf, "%s:%s", s1, s2);
  char *s = agstrdup(G, agxbuse(&buf));
  agstrfree (G,s1);
  agstrfree (G,s2);
  agxbfree(&buf);
  return s;
}
 
 
static void edgerhs(Agnode_t *tail, char *tport, item *hlist, char *key)
{
        Agnode_t                *head;
        Agraph_t                *subg;
        item                    *hptr;
 
        if (hlist->tag == T_subgraph) {
                subg = hlist->u.subg;
                for (head = agfstnode(subg); head; head = agnxtnode(subg,head))
                        newedge(tail, tport, agsubnode(S->g, head, 0), NULL, key);
        }
        else {
                for (hptr = hlist->u.list; hptr; hptr = hptr->next)
                        newedge(tail, tport, agsubnode(S->g, hptr->u.n, 0), hptr->str, key);
        }
}
 
static void mkport(Agedge_t *e, char *name, char *val)
{
        Agsym_t *attr;
        if (val) {
                if ((attr = agattr(S->g,AGEDGE,name,NULL)) == NULL)
                        attr = agattr(S->g,AGEDGE,name,"");
                agxset(e,attr,val);
        }
}
 
static void newedge(Agnode_t *t, char *tport, Agnode_t *h, char *hport, char *key)
{
        Agedge_t        *e;
 
        e = agedge(S->g, t, h, key, 1);
        if (e) {                /* can fail if graph is strict and t==h */
                char    *tp = tport;
                char    *hp = hport;
                if ((agtail(e) != aghead(e)) && (aghead(e) == t)) {
                        /* could happen with an undirected edge */
                        char    *temp;
                        temp = tp; tp = hp; hp = temp;
                }
                mkport(e,TAILPORT_ID,tp);
                mkport(e,HEADPORT_ID,hp);
                applyattrs(e);
        }
}
 
/* graphs and subgraphs */
 
 
static void startgraph(char *name, bool directed, bool strict)
{
        if (G == NULL) {
                SubgraphDepth = 0;
                Agdesc_t req = {.directed = directed, .strict = strict, .maingraph = true};
                Ag_G_global = G = agopen(name,req,Disc);
        }
        else {
                Ag_G_global = G;
        }
        S = push(S,G);
        agstrfree(NULL,name);
}
 
static void endgraph(void)
{
        aglexeof();
        aginternalmapclearlocalnames(G);
}
 
static void opensubg(char *name)
{
  if (++SubgraphDepth >= YYMAXDEPTH/2) {
    agerrorf("subgraphs nested more than %d deep", YYMAXDEPTH);
  }
        S = push(S, agsubg(S->g, name, 1));
        agstrfree(G,name);
}
 
static void closesubg(void)
{
        Agraph_t *subg = S->g;
  --SubgraphDepth;
        S = pop(S);
        S->subg = subg;
        assert(subg);
}
 
static void freestack(void)
{
        while (S) {
                deletelist(&(S->nodelist));
                deletelist(&(S->attrlist));
                deletelist(&(S->edgelist));
                S = pop(S);
        }
}
 
extern FILE *aagin;
Agraph_t *agconcat(Agraph_t *g, void *chan, Agdisc_t *disc)
{
        aagin = chan;
        G = g;
        Ag_G_global = NULL;
        Disc = (disc? disc :  &AgDefaultDisc);
        aglexinit(Disc, chan);
        aagparse();
        if (Ag_G_global == NULL) aglexbad();
        return Ag_G_global;
}
 
Agraph_t *agread(void *fp, Agdisc_t *disc) {return agconcat(NULL,fp,disc); }