shithub: pprolog

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Make parse return a list of clauses. Also pretty print the entire list of clauses.

--- a/example.pl

+++ b/example.pl

@@ -16,6 +16,7 @@

 could_be_friends(Person1, Person2) :-

 	likes(Person1, Thing1),

 	likes(Person2, Thing2),

+	!,

 	Thing1 = Thing2.

 list1(A) :- A = [1,2,3,4].

--- a/fns.h

+++ b/fns.h

@@ -1,5 +1,5 @@

 /* parser.c */

-void parse(int);

+Term *parse(int);

 /* prettyprint.c */

 Rune *prettyprint(Term *);

--- a/main.c

+++ b/main.c

@@ -29,7 +29,10 @@

 		int fd = open(parsetestfile, OREAD);

 		if(fd < 0)

 			exits("open");

-		parse(fd);

+		Term *prog = parse(fd);

+		Term *clause;

+		for(clause = prog; clause != nil; clause = clause->next)

+			print("%S.\n", prettyprint(clause));

 	}

 	exits(nil);

--- a/parser.c

+++ b/parser.c

@@ -7,9 +7,6 @@

 #define PrecedenceLevels 1200

-/* The parser doesn't produce an ast for now, it only acts like a recognizer,

-   printing errors if it fails */

-

 typedef struct Token Token;

 typedef struct Operator Operator;

 typedef struct OpInfo OpInfo;

@@ -79,50 +76,48 @@

 Term *parseoperators(Term *);

 void match(int);

 void syntaxerror(char *);

-void prologtext(void);

+Term *prologtext(void);

-void

+Term *

 parse(int fd)

 {

 	parsein = Bfdopen(fd, OREAD);

 	if(parsein == nil){

 		print("Could not open file\n");

-		return;

+		return nil;

 	}

 	initoperators();

 	nexttoken();

-	prologtext();

+	return prologtext();

 }

-void

+Term *

 prologtext(void)

 {

 	if(lookahead.tag == EofTok)

-		return;

+		return nil;

 	Term *t = fullterm(AtomTok, L".", nil);

+	if(lookahead.tag == AtomTok && runestrcmp(lookahead.text, L".") == 0)

+		match(AtomTok);

+	else

+		syntaxerror("prologtext");

 	if(t->tag == CompoundTerm && runestrcmp(t->text, L":-") == 0 && t->arity == 1){

 		/* A Directive */

 		print("Got directive: %S\n", prettyprint(t));

+		t = prologtext();

 	}else if(t->tag == CompoundTerm && runestrcmp(t->text, L":-") == 0 && t->arity == 2){

-		/* A clause with a body */

-		print("Got clause with body: %S\n", prettyprint(t));

+		t->next = prologtext();

 	}else if(t->tag == AtomTerm || t->tag == CompoundTerm){

-		/* A clause without a body */

-		print("Got clause without body: %S\n", prettyprint(t));

+		t->next = prologtext();

 	}else{

 		print("Expected directive or clause as toplevel\n");

 		syntaxerror("prologtext");

 	}

-	if(lookahead.tag == AtomTok && runestrcmp(lookahead.text, L".") == 0)

-		match(AtomTok);

-	else

-		syntaxerror("prologtext");

-

-	prologtext();

+	return t;

 }

 Term *

@@ -567,7 +562,7 @@

 	}

 	/* Other */

-	if(runestrchr(L",.()]}|", peek)){

+	if(runestrchr(L",.()]}|!", peek)){

 		switch(peek){

 		case L',': lookahead.tag = CommaTok; break;

 		case L'(': lookahead.tag = ParenLeftTok; break;

@@ -575,6 +570,7 @@

 		case L']': lookahead.tag = SquareBracketRightTok; break;

 		case L'}': lookahead.tag = CurlyBracketRightTok; break;

 		case L'|': lookahead.tag = PipeTok; break;

+		case L'!': lookahead.tag = AtomTok; lookahead.text = runestrdup(L"!"); break;

 		}

 		return;

 	}