Merge pull request #26 from quephird/cannot_initialize_an_empty_list

Addressed bug in parser and added supporting tests.
quephird · Mar 22, 2024 · 7c68a60 · 7c68a60
2 parents f186e05 + 7f7af93
commit 7c68a60
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Showing 3 changed files with 34 additions and 4 deletions.
diff --git a/slox/Parser.swift b/slox/Parser.swift
@@ -552,7 +552,7 @@ struct Parser {
             return nil
         }
 
-        let args = try parseArguments()
+        let args = try parseArguments(endTokenType: .rightParen)
 
         guard currentTokenMatchesAny(types: [.rightParen]) else {
             throw ParseError.missingCloseParenAfterArguments(currentToken)
@@ -662,7 +662,7 @@ struct Parser {
             return nil
         }
 
-        let elements = try parseArguments()
+        let elements = try parseArguments(endTokenType: .rightBracket)
 
         guard currentTokenMatchesAny(types: [.rightBracket]) else {
             throw ParseError.missingClosingBracket(previousToken)
@@ -728,9 +728,9 @@ struct Parser {
         return parameters
     }
 
-    mutating private func parseArguments() throws -> [Expression] {
+    mutating private func parseArguments(endTokenType: TokenType) throws -> [Expression] {
         var args: [Expression] = []
-        if currentToken.type != .rightParen {
+        if currentToken.type != endTokenType {
             repeat {
                 let newArg = try parseExpression()
                 args.append(newArg)

diff --git a/sloxTests/InterpreterTests.swift b/sloxTests/InterpreterTests.swift
@@ -467,6 +467,18 @@ baz[1][1]
         XCTAssertEqual(actual, expected)
     }
 
+    func testInterpretCreateAnEmptyList() throws {
+        let input = """
+var quux = [];
+quux.count
+"""
+
+        let interpreter = Interpreter()
+        let actual = try interpreter.interpretRepl(source: input)
+        let expected: LoxValue = .number(0)
+        XCTAssertEqual(actual, expected)
+    }
+
     func testInterpretExpressionWithListSubscriptingMethodInvocationAndPropertyGetting() throws {
         let input = """
 class Foo { }

diff --git a/sloxTests/ParserTests.swift b/sloxTests/ParserTests.swift
@@ -1215,4 +1215,22 @@ final class ParserTests: XCTestCase {
             XCTAssertEqual(actualError as! ParseError, expectedError)
         }
     }
+
+    func testParseAnEmptyList() throws {
+        // [ ]
+        let tokens: [Token] = [
+            Token(type: .leftBracket, lexeme: "[", line: 1),
+            Token(type: .rightBracket, lexeme: "]", line: 1),
+            Token(type: .eof, lexeme: "", line: 1)
+        ]
+
+        var parser = Parser(tokens: tokens)
+        let actual = try parser.parse()
+        let expected: [Statement] = [
+            .expression(
+                .list([
+                ]))
+        ]
+        XCTAssertEqual(actual, expected)
+    }
 }