basic: fixed NEXT, expectTokens()

src/common/basic/compiler.ts

@@ -31,6 +31,7 @@ export interface BASICOptions {
     numericPadding : boolean;           // " " or "-" before and " " after numbers?
     // CONTROL FLOW
     testInitialFor : boolean;           // can we skip a NEXT statement? (can't interleave tho)
+    optionalNextVar : boolean;          // can do NEXT without variable
     ifElse : boolean;                   // IF...ELSE construct
     // MISC
     commandsPerSec? : number;           // how many commands per second?
@@ -290,7 +291,7 @@ export class BASICParser {
     }
     compileError(msg: string, loc?: SourceLocation) {
         if (!loc) loc = this.peekToken().$loc;
-        this.errors.push({path:loc.path, line:loc.line, label:loc.label, start:loc.start, end:loc.end, msg:msg});
+        this.errors.push({path:loc.path, line:loc.line, label:this.curlabel, start:loc.start, end:loc.end, msg:msg});
         throw new CompileError(`${msg} (line ${loc.line})`); // TODO: label too?
     }
     dialectError(what: string, loc?: SourceLocation) {
@@ -308,6 +309,14 @@ export class BASICParser {
         }
         return tok;
     }
+    expectTokens(strlist: string[], msg?: string) : Token {
+        var tok = this.consumeToken();
+        var tokstr = tok.str;
+        if (strlist.indexOf(tokstr) < 0) {
+            this.compileError(msg || `There should be one of "${strlist}" here.`);
+        }
+        return tok;
+    }
     peekToken(): Token {
         var tok = this.tokens[0];
         return tok ? tok : this.eol;
@@ -654,11 +663,10 @@ export class BASICParser {
         var cond = this.parseExpr();
         var iftrue: Statement[];
         // we accept GOTO or THEN if line number provided
-        if (this.peekToken().str == 'GOTO') this.consumeToken();
+        var thengoto = this.expectTokens(['THEN','GOTO']);
-        else this.expectToken('THEN');
         var lineno = this.peekToken();
         // assume GOTO if number given after THEN
-        if (lineno.type == TokenType.Int) {
+        if (lineno.type == TokenType.Int && thengoto.str == 'THEN') {
             this.pushbackToken({type:TokenType.Ident, str:'GOTO', $loc:lineno.$loc});
         }
         // add fake ":"
@@ -709,7 +717,7 @@ export class BASICParser {
         var prompt = this.consumeToken();
         var promptstr;
         if (prompt.type == TokenType.String) {
-            this.expectToken(';');
+            this.expectTokens([';', ',']);
             promptstr = stripQuotes(prompt.str);
         } else {
             this.pushbackToken(prompt);
@@ -884,6 +892,7 @@ export const ECMA55_MINIMAL : BASICOptions = {
     numericPadding : true,
     checkOverflow : true,
     testInitialFor : true,
+    optionalNextVar : false,
     ifElse : false,
     bitwiseLogic : false,
 }
@@ -917,6 +926,7 @@ export const BASICODE : BASICOptions = {
     numericPadding : true,
     checkOverflow : true,
     testInitialFor : true,
+    optionalNextVar : false,
     ifElse : false,
     bitwiseLogic : false,
 }
@@ -952,6 +962,7 @@ export const ALTAIR_BASIC41 : BASICOptions = {
     numericPadding : true,
     checkOverflow : true,
     testInitialFor : false,
+    optionalNextVar : true,
     //multipleNextVars : true, // TODO: not supported
     ifElse : true,
     bitwiseLogic : true,
@@ -994,6 +1005,7 @@ export const APPLESOFT_BASIC : BASICOptions = {
     numericPadding : false,
     checkOverflow : true,
     testInitialFor : false,
+    optionalNextVar : true,
     ifElse : false,
     bitwiseLogic : false,
 }
@@ -1023,6 +1035,7 @@ export const MODERN_BASIC : BASICOptions = {
     numericPadding : false,
     checkOverflow : true,
     testInitialFor : true,
+    optionalNextVar : true,
     ifElse : true,
     bitwiseLogic : true,
 }

src/common/basic/runtime.ts

@@ -423,7 +423,7 @@ export class BASICRuntime {
     }
 
     nextForLoop(name) {
-        var fl = this.forLoops[name];
+        var fl = this.forLoops[name || (this.opts.optionalNextVar && this.topForLoopName)];
         if (!fl) this.runtimeError(`I couldn't find a FOR for this NEXT.`)
         fl.$next(name);
     }

src/platform/basic.ts

@@ -179,7 +179,7 @@ class BASICPlatform implements Platform {
             ForLoops: this.runtime.forLoops,
             ReturnStack: this.runtime.returnStack,
             NextDatum: this.runtime.datums[this.runtime.dataptr],
-            Dialect: this.runtime.opts,
+            Options: this.runtime.opts,
             Internals: this.runtime,
         }
     }