shithub: pprolog

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Fix some parser errors, and accept clauses without a body

--- a/example.pl

+++ b/example.pl

@@ -2,4 +2,4 @@

 math(A,B,C,D) :- D is A + B + C * A.

-true :- 1 = 1.

+true.

\ No newline at end of file

--- a/parser.c

+++ b/parser.c

@@ -99,19 +99,19 @@

 		return;

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

-	if(t->tag != CompoundTerm || runestrcmp(t->text, L":-") != 0 || !(t->arity == 1 || t->arity == 2)){

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

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

-		print("Tag=%d arity=%d text=\"%S\"\n", t->tag, t->arity, t->text);

-		syntaxerror("prologtext");

-	}

-	if(t->arity == 1){

-		/* A directive */

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

+		/* A Directive */

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

+	}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));

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

+		/* A clause without a body */

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

 	}else{

-		/* A clause */

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

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

+		syntaxerror("prologtext");

 	}

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

@@ -537,6 +537,11 @@

 	exits("lexer");

 Functor:

+	if(peek == Beof){

+		Bgetrune(parsein);

+		return;

+	}

+

 	peek = Bgetrune(parsein);

 	if(peek == L'(')

 		lookahead.tag = FunctorTok;

@@ -556,6 +561,6 @@

 void

 syntaxerror(char *where)

 {

-	print("Syntax error: Unexpected %d token in %s\n", lookahead.tag, where);

+	print("Syntax error: Unexpected %d (%S) token in %s\n", lookahead.tag, lookahead.text, where);

 	exits("syntax error");

 }

\ No newline at end of file