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Use eval() to parse constants

--- a/eval.c

+++ b/eval.c

@@ -8,16 +8,13 @@

 static ByteCode *codegen(Session *, Module *, Ast *);

 static void *evalbc(Session *, Module *, ByteCode *);

-void

+void *

 eval(Session *s, Ast *a)

 {

 	/* Evaluate some ast in module m in session s. */

 	Module *m = s->modules->modules[0]; /* TODO: this isn't nice */

 	ByteCode *code = codegen(s, m, a);

-	void *v = evalbc(s, m, code);

-

-	if(v)

-		appendlog(s, printval(v));

+	return evalbc(s, m, code);

 }

 static void

--- a/fns.h

+++ b/fns.h

@@ -8,7 +8,7 @@

 char *printarray(Array *);

 /* eval.c */

-void eval(Session *s, Ast *);

+void *eval(Session *s, Ast *);

 /* fs.c */

 Qid freshobjqid(void);

@@ -58,5 +58,5 @@

 /* value.c */

 char *printval(void *);

-void *parseval(char *, char **);

+void *parseval(Session *s, char *, char **);

--- a/fs.c

+++ b/fs.c

@@ -263,13 +263,14 @@

 symbolrw(Req *r)

 {

 	Aux *aux = r->fid->aux;

-	Symbol *s = aux->symbol;

+	Session *session = aux->session;

+	Symbol *symb = aux->symbol;

 	char *err = nil;

 	if(r->ifcall.type == Tread){

 		/* Pretty print the value and readstr() it. */

 		if(aux->cachestr == nil)

-			aux->cachestr = printval(s->value);

+			aux->cachestr = printval(symb->value);

 		readstr(r, aux->cachestr);

 		if(r->ofcall.count == 0){

 			free(aux->cachestr);

@@ -277,10 +278,10 @@

 		}

 	}else{ /* Twrite */

 		char *buf = requeststr(r);

-		void *v = parseval(buf, &err);

+		void *v = parseval(session, buf, &err);

 		free(buf);

 		if(!err)

-			symset(s->table, s->id, v);

+			symset(symb->table, symb->id, v);

 	}

 	return err;

 }

--- a/session.c

+++ b/session.c

@@ -57,7 +57,9 @@

 				goto error;

 			debugast(ast, 0);

-			eval(s, ast);

+			void *val = eval(s, ast);

+			if(val)

+				appendlog(s, printval(val));

 		}

 	}

 }

--- a/value.c

+++ b/value.c

@@ -7,7 +7,7 @@

 /* Anything that can have a name in LPA: Arrays, functions, ... */

-static Array *evalconstast(Ast *);

+static int checkexpr(Ast *);

 char *

 printval(void *v)

@@ -26,7 +26,7 @@

 }

 void *

-parseval(char *buf, char **errp)

+parseval(Session *s, char *buf, char **errp)

 {

 	Ast *ast;

 	void *val = nil;

@@ -34,13 +34,9 @@

 	TokenList *tokens = scan(buf, errp);

 	if(tokens == nil)

 		goto end;

-	ast = parse(tokens, 0, errp);

+	ast = parse(tokens, nil, errp);

 	if(ast == nil)

 		goto end;

-	debugast(ast, 0);

-	/* Check that the ast is either a single function definition,

-	 * or a constant (stranding is OK).

-	 */

 	if(!(ast->tag == AstProg && ast->childcount == 1)){

 		*errp = "Expected single value or function definition";

@@ -48,24 +44,31 @@

 	}

 	ast = ast->children[0];

+	if(checkexpr(ast))

+		val = eval(s, ast);

+	else

+		*errp = "Expected value or function definition";

+end:

+	return val;

+}

+

+static int

+checkexpr(Ast *ast)

+{

 	switch(ast->tag){

 	case AstConst:

-	case AstStrand:

-		val = evalconstast(ast);

-		if(val == nil)

-			*errp = "Expected constant expression";

-		break;

 	case AstFunc:

-		*errp = "Functions not supported yet";

-		break;

+		return 1;

+	case AstStrand:

+		for(uvlong i = 0; i < ast->childcount; i++){

+			if(!checkexpr(ast->children[i]))

+				return 0;

+		}

+		return 1;

 	default:

-		*errp = "Expected constant or function definition";

-		break;

+		return 0;

 	}

-end:

-	return val;

 }

-

 static Array *

 evalconstast(Ast *ast)

 {