From 14cec6e77042ad9a3d2cfe4f70f6807b813f3ef8 Mon Sep 17 00:00:00 2001
From: "Amy J. Ko" <ajko@uw.edu>
Date: Wed, 10 Jul 2024 15:45:10 -0700
Subject: [PATCH] Fixed parsing bug that prevented complete parsing of the
 program.

---
 CHANGELOG.md                  |  1 +
 src/parser/Parser.test.ts     | 12 +++++++++++-
 src/parser/Tokens.ts          |  2 +-
 src/parser/parseExpression.ts | 24 ++++++++++++++++++------
 src/parser/parseProgram.ts    |  3 +--
 5 files changed, 32 insertions(+), 10 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 019d83fc3..b952d2b89 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -8,6 +8,7 @@ Dates are in `YYYY-MM-DD` format and versions are in [semantic versioning](http:
 ### Fixed
 
 -   [#514](https://github.com/wordplaydev/wordplay/issues/514) Fixed cursor position on hidden language tags.
+-   Fixed parsing bug that prevented complete parsing of the program.
 
 ## 0.10.4 2024-07-08
 
diff --git a/src/parser/Parser.test.ts b/src/parser/Parser.test.ts
index edaea329a..797217282 100644
--- a/src/parser/Parser.test.ts
+++ b/src/parser/Parser.test.ts
@@ -11,7 +11,7 @@ import NumberLiteral from '@nodes/NumberLiteral';
 import NumberType from '@nodes/NumberType';
 import NameType from '@nodes/NameType';
 import NoneType from '@nodes/NoneType';
-import { toProgram } from './parseProgram';
+import parseProgram, { toProgram } from './parseProgram';
 import Program from '@nodes/Program';
 import StreamType from '@nodes/StreamType';
 import TableType from '@nodes/TableType';
@@ -384,3 +384,13 @@ test('unparsables in docs', () => {
     expect(doc.markup.paragraphs[0].segments[2]).toBeInstanceOf(Token);
     expect(doc.markup.paragraphs[0].segments.length).toBe(3);
 });
+
+test('unparsables in blocks', () => {
+    const program = parseProgram(toTokens('test: Phrase(\\\\)\ntest'));
+    expect(program).toBeInstanceOf(Program);
+    expect(program.expression).toBeInstanceOf(Block);
+    expect(program.expression.statements[0]).toBeInstanceOf(Bind);
+    expect(program.expression.statements[1]).toBeInstanceOf(
+        UnparsableExpression,
+    );
+});
diff --git a/src/parser/Tokens.ts b/src/parser/Tokens.ts
index 8c08db146..9f31f08dc 100644
--- a/src/parser/Tokens.ts
+++ b/src/parser/Tokens.ts
@@ -45,7 +45,7 @@ export default class Tokens {
     }
 
     peekUnread() {
-        return this.#unread;
+        return this.#unread.slice();
     }
 
     /** Returns true if the token list isn't empty. */
diff --git a/src/parser/parseExpression.ts b/src/parser/parseExpression.ts
index a6c1a838a..32bbb53a0 100644
--- a/src/parser/parseExpression.ts
+++ b/src/parser/parseExpression.ts
@@ -62,6 +62,7 @@ import Spread from '../nodes/Spread';
 import Otherwise from '@nodes/Otherwise';
 import Match from '@nodes/Match';
 import Input from '@nodes/Input';
+import type Token from '@nodes/Token';
 
 export function toExpression(code: string): Expression {
     return parseExpression(toTokens(code));
@@ -128,12 +129,23 @@ export function parseBlock(
             ((root && !doc) ||
                 (!root && !doc && tokens.nextIsnt(Sym.EvalClose)) ||
                 (doc && tokens.nextIsnt(Sym.Code))),
-        () =>
-            statements.push(
-                nextIsBind(tokens, true)
-                    ? parseBind(tokens)
-                    : parseExpression(tokens),
-            ),
+        () => {
+            const next = nextIsBind(tokens, true)
+                ? parseBind(tokens)
+                : parseExpression(tokens);
+            statements.push(next);
+            // Did we get an unparsable expression with no tokens? Read until we get to the block close or the end of the
+            // program. If we don't do this, the we will stop reading statements and will not parse the remainder of the program.
+            if (
+                next instanceof UnparsableExpression &&
+                next.unparsables.length === 0
+            ) {
+                const unparsed: Token[] = [];
+                while (tokens.hasNext() && tokens.nextIsnt(Sym.EvalClose))
+                    unparsed.push(tokens.read());
+                statements.push(new UnparsableExpression(unparsed));
+            }
+        },
     );
 
     const close = root
diff --git a/src/parser/parseProgram.ts b/src/parser/parseProgram.ts
index 79753db90..9252bc8e1 100644
--- a/src/parser/parseProgram.ts
+++ b/src/parser/parseProgram.ts
@@ -22,8 +22,7 @@ export default function parseProgram(tokens: Tokens, doc = false): Program {
 
     const block = parseBlock(tokens, BlockKind.Root, doc);
 
-    // If the next token is the end, we're done! Otherwise, read all of the remaining
-    // tokens and bundle them into an unparsable.
+    // If the next token is the end, we're done!
     const end = tokens.nextIsEnd() ? tokens.read(Sym.End) : undefined;
 
     return new Program(docs, borrows, block, end);