fix: ELSE and IF ELSE statement

Fixes remy/vscode-nextbasic#45

__tests__/bas2txt.test.js

@@ -65,3 +65,11 @@ test('comments are parsed as plain text', (t) => {
   res = line2txt(src.basic);
   t.is(res, text, 'comments are untouched with REM');
 });
+
+test('else if (2.08)', (t) => {
+  let text, src, res;
+  text = '20 ELSE IF 1 < 2 PRINT "ELSE"';
+  src = parseLineWithData(text); // to binary
+  res = line2txt(src.basic); // to text
+  t.is(res, text, 'new IF correctly rendered');
+});

__tests__/peek-token.test.js

@@ -0,0 +1,61 @@
+import test from 'ava';
+import { Statement } from '../txt2bas';
+
+/**
+ * @param {require("~/index.d.ts").Token} token string
+ * @returns {string}
+ */
+function text(token) {
+  return token.text || token.value;
+}
+
+test('multi statement peek', (t) => {
+  let src,
+    token,
+    peek,
+    pos = 0;
+  src = '10 IF %z THEN: ELSE IF %z=34 THEN: ELSE PRINT "3"';
+
+  const statement = new Statement(src);
+
+  token = statement.nextToken(); // move to IF
+  t.is(text(token), 'IF');
+  pos = statement.pos;
+  peek = statement.peekToken(pos);
+  t.is(text(peek), '%');
+  pos = peek.pos;
+  peek = statement.peekToken(pos);
+  t.is(text(peek), 'z');
+  pos = peek.pos;
+  peek = statement.peekToken(pos);
+  t.is(text(peek), 'THEN');
+  pos = peek.pos;
+  peek = statement.peekToken(pos);
+  t.is(peek.name, 'STATEMENT_SEP'); // should be nothing
+});
+
+test.only('multi statement peek with preview', (t) => {
+  let src, token, hasThen, statement;
+
+  src = '10 IF %z THEN: ELSE IF %z=34 THEN: ELSE PRINT "3"';
+  statement = new Statement(src);
+  token = statement.nextToken(); // move to IF
+  t.is(text(token), 'IF');
+  hasThen = statement.peekStatementContains('THEN');
+
+  t.is(hasThen, true, 'first IF contains THEN');
+
+  src = '10 ELSE IF %z=34 THEN: ELSE PRINT "3"';
+  statement = new Statement(src);
+  token = statement.nextToken(); // move to ELSE
+  t.is(text(token), 'ELSE');
+  hasThen = statement.peekStatementContains('THEN');
+  t.is(hasThen, true, 'first IF contains THEN');
+
+  src = '20 ELSE IF 1 < 2 PRINT "ELSE"';
+  statement = new Statement(src);
+  token = statement.nextToken(); // move to ELSE
+  t.is(text(token), 'ELSE');
+  hasThen = statement.peekStatementContains('THEN');
+  t.is(hasThen, false, 'first IF does not contain THEN');
+});

__tests__/txt2bas.test.js

@@ -101,9 +101,9 @@ test('comments', (t) => {
 });
 
 test('end with $', (t) => {
-  let src = '202 IF INKEY$="s"';
+  let src = '202 IF INKEY$="s" THEN';
   let expect = [
-    0x00, 0xca, 0x07, 0x00, 0xfa, 0xa6, 0x3d, 0x22, 0x73, 0x22, 0x0d,
+    0x00, 0xca, 0x08, 0x00, 0xfa, 0xa6, 0x3d, 0x22, 0x73, 0x22, 0xcb, 0x0d,
   ];
 
   const res = Array.from(parseLine(src));
@@ -293,13 +293,16 @@ test('INT function', (t) => {
   t.is(token.name, 'NUMBER');
 });
 
-test('ELSE IF', (t) => {
+test('ELSE IF (2.08)', (t) => {
   let src, res;
+
   src = '20 ELSE IF 1 < 2 PRINT "ELSE"';
   res = parseLines(src).statements[0];
 
+  console.log(res.tokens[1]);
+
   t.is(res.tokens[0].text, 'ELSE', 'has else');
-  t.is(res.tokens[1].text, 'IF', 'then if');
+  t.is(res.tokens[1].text, 'IF', 'then "special" if');
   t.is(res.tokens[1].value, 0x83, 'correct IF value for following ELSE');
 });
 

cli/index.js

@@ -222,7 +222,7 @@ function help(type) {
   console.log('');
   if (type === 'txt') {
     console.log('  -f 3dos|tap ... set the output format');
-    console.log('  -t ............ parse and validate the NextBASIC');
+    console.log('  -t ............ test and validate the NextBASIC');
     console.log('  -bank ......... output LOAD "file" BANK format');
     console.log('  -C ............ strip comments from output');
     console.log('  -define........ support #define constant transforms');

codes.js

@@ -9,7 +9,7 @@ export default {
   // new in 2.08
   0x81: 'TIME',
   0x82: 'PRIVATE',
-  0x83: 'IF', // internal use only: displays as IF (which is managed here), but is converted from 0x83 via the aliases in op-table
+  0x83: 'IF', // internal use only: displays as IF (which is managed here), but is converted from 0x83 via the aliases in op-table as 'ELSE IF'
   0x84: 'ENDIF',
   0x85: 'EXIT',
   0x86: 'REF',

index.d.ts

@@ -0,0 +1,15 @@
+type Token = {
+  name: string;
+  value: number | string;
+  text: string;
+  numeric: number;
+  integer: boolean;
+};
+
+type ParsedBasic = {
+  basic: Uint8Array;
+  line: string;
+  length: number;
+  lineNumber: number;
+  tokens: Token[];
+};

txt2bas/index.js

@@ -5,6 +5,7 @@ import tests from '../chr-tests';
 import { TEXT } from '../unicode';
 
 import { validateLineNumber, validateStatement } from './validator';
+import * as parser from '../parser-version';
 
 import {
   DEFINE,
@@ -25,6 +26,7 @@ import {
   DEFFN_SIG,
   DEF_FN_ARG,
   IF,
+  ELSEIF,
   DEFFN_ARGS,
   NUMBER_DATA,
   KEYWORD,
@@ -561,8 +563,76 @@ export class Statement {
     return token;
   }
 
+  /**
+   *
+   * @param {Token} token
+   * @returns {Token}
+   */
   manageTokenState(token) {
-    if (!token) return;
+    // if !token, it could be that it wasn't recognised
+    if (!token) {
+      // console log the state?
+      return;
+    }
+
+    // TODO if the token isn't recognised, try to get the DEF FN or other
+    if (token.value === 'DEF') {
+      // this is more likely to be a DEF FN - so let's peek the next token
+      const peek = this.peekToken(this.pos);
+      if (peek.text === 'FN') {
+        token = {
+          name: KEYWORD,
+          text: 'DEF FN',
+          value: opTable['DEF FN'],
+          pos: this.pos,
+        };
+        this.pos = peek.pos; // move to the end of DEF FN
+      }
+    }
+
+    if (token.value === 'OPEN' || token.value === 'CLOSE') {
+      // this is more likely to be a OPEN # or CLOSE #
+      const peek = this.peek();
+
+      if (peek === '#') {
+        token = {
+          name: KEYWORD,
+          text: `${token.value} ${peek}`,
+          value: opTable[`${token.value} ${peek}`],
+          pos: this.pos,
+        };
+        this.pos += 2; // allow for the space
+      }
+    }
+
+    if (token.value === 'GO') {
+      // this is more likely to be a GO TO or GO SUB
+      const peek = this.peekToken(this.pos);
+      // note: peek.value when it's an identify
+      // peek.text when it's a keyword
+      if (peek.value === 'SUB' || peek.text === 'TO') {
+        token = {
+          name: KEYWORD,
+          text: `GO ${peek.text || peek.value}`,
+          value: opTable[`GO ${peek.text || peek.value}`],
+          pos: this.pos,
+        };
+        this.pos = peek.pos; // move to the end of DEF FN
+      }
+    }
+
+    if (parser.getParser() >= parser.v208 && token.text === 'IF') {
+      // look for ELSE before hand
+      const hasThen = this.peekStatementContains('THEN');
+      if (!hasThen) {
+        token = {
+          name: KEYWORD,
+          text: codes[opTable[ELSEIF]],
+          value: opTable[ELSEIF],
+          pos: this.pos,
+        };
+      }
+    }
 
     if (token.name !== WHITE_SPACE) {
       if (token.value !== '%') this.next = null; // always reset
@@ -631,6 +701,10 @@ export class Statement {
         this.in.push(IF);
       }
 
+      if (token.value === opTable.ELSEIF) {
+        this.in.push(ELSEIF);
+      }
+
       if (token.value === opTable.UNTIL) {
         this.in.push(UNTIL);
       }
@@ -640,6 +714,11 @@ export class Statement {
         this.inIntExpression = false;
       }
 
+      if (token.value === opTable.ENDIF) {
+        this.popTo(ELSEIF);
+        this.inIntExpression = false;
+      }
+
       if (token.value === opTable.BIN) {
         this.next = BINARY;
       }
@@ -656,7 +735,7 @@ export class Statement {
     }
 
     if (token.value === '=') {
-      if (!this.isIn(IF) && !this.isIn(UNTIL)) {
+      if (!this.isIn(IF) && !this.isIn(ELSEIF) && !this.isIn(UNTIL)) {
         this.inIntExpression = false;
       }
     }
@@ -763,33 +842,52 @@ export class Statement {
   }
 
   peekToken(at = this.pos) {
-    let pos = at + 1;
-    const start = at;
-    while (
-      pos < this.line.length &&
-      !tests._isSpace(this.line.charAt(pos)) &&
-      !tests._isDigit(this.line.charAt(pos))
-    ) {
-      pos++;
+    // cache state
+    const cache = {
+      pos: this.pos,
+      inIntExpression: this.inIntExpression,
+      lastToken: this.lastToken,
+      tokens: Array.from(this.tokens),
+    };
+
+    this.pos = at;
+
+    /** @type {Token} */
+    let token = this.token();
+
+    if (!token) {
+      return null;
     }
-    return this.line.substring(start, pos);
+
+    if (token.name === WHITE_SPACE) {
+      token = this.token();
+    }
+
+    let tokenPosition = this.pos;
+
+    // restore state
+    this.pos = cache.pos;
+    this.inIntExpression = cache.inIntExpression;
+    this.lastToken = cache.lastToken;
+    this.tokens = cache.tokens;
+
+    return { ...token, pos: tokenPosition };
   }
 
-  peekPrevToken(at = this.pos) {
-    let pos = at - 1;
-    const end = pos;
-    let allowSpace = true;
-    while (pos >= 0 || tests._isDigit(this.line.charAt(pos))) {
-      if (tests._isSpace(this.line.charAt(pos)) && !allowSpace) {
-        pos++;
-        break;
-      }
-      if (tests._isSpace(this.line.charAt(pos))) {
-        allowSpace = false;
-      }
-      pos--;
+  // mostly only used to search for THEN
+  peekStatementContains(keyword) {
+    let frag = this.line.substring(this.pos);
+
+    frag = frag.replace(/".*?"/g, '').trim();
+    frag = frag.split(/\b/).map((_) => _.trim().toUpperCase());
+    let end = frag.indexOf(':');
+    if (end === -1) {
+      end = undefined;
     }
-    return this.line.substring(pos, end);
+    frag = frag.slice(0, end);
+
+    // strip out any quoted strings
+    return frag.includes(keyword);
   }
 
   findOpCode(endPos) {
@@ -805,27 +903,6 @@ export class Statement {
       return false;
     }
 
-    if (curr === 'IF') {
-      // look for ELSE before hand
-      const prev = this.peekPrevToken();
-      if (prev === 'ELSE') {
-        curr = 'ELSE IF';
-      }
-    }
-
-    // be wary that this could be something like `DEF FN`
-    else if (peek === ' ' && !opTable[curr]) {
-      const next = this.peekToken(endPos + 1).toUpperCase();
-      const test = `${curr} ${next}`;
-
-      if (opTable[test]) {
-        curr = test;
-        endPos = endPos + 1 + next.length;
-      } else {
-        return false;
-      }
-    }
-
     if (opTable[curr] !== undefined) {
       const token = {
         name: KEYWORD,

txt2bas/types.js

@@ -6,6 +6,7 @@ export const IDENTIFIER = 'IDENTIFIER';
 export const DEFFN = 'DEFFN';
 export const DEFFN_SIG = 'DEFFN_SIG';
 export const IF = 'IF';
+export const ELSEIF = 'ELSE IF';
 export const FOR = 'FOR';
 export const OUTER_IF = 'OUTER_IF';
 export const DEFFN_ARGS = 'DEFFN_ARGS';