Add distinct error type for invalid escape sequences

nicklockwood · nicklockwood · commit 59c49c024b8c · 2021-11-01T23:45:09.000Z
diff --git a/ShapeScript/Lexer.swift b/ShapeScript/Lexer.swift
@@ -88,6 +88,7 @@ public enum LexerErrorType: Equatable {
     case invalidColor(String)
     case unexpectedToken(String)
     case unterminatedString
+    case invalidEscapeSequence(String)
 }
 
 public struct LexerError: Error, Equatable {
@@ -107,6 +108,11 @@ public struct LexerError: Error, Equatable {
             return "Unexpected token '\(token)'"
         case .unterminatedString:
             return "Unterminated string literal"
+        case let .invalidEscapeSequence(sequence):
+            let sequence = sequence.unicodeScalars.contains {
+                CharacterSet.whitespaces.contains($0)
+            } ? "'\(sequence)'" : sequence
+            return "Invalid escape sequence \(sequence)"
         }
     }
 
@@ -123,6 +129,8 @@ public struct LexerError: Error, Equatable {
             return nil
         case .unterminatedString:
             return "Try adding a closing \" (double quote) at the end of the line."
+        case .invalidEscapeSequence:
+            return "Supported sequences are \\\", \\n and \\\\."
         }
     }
 
@@ -337,7 +345,7 @@ private extension Substring {
                 break loop
             default:
                 let range = start.index(before: startIndex) ..< index(after: startIndex)
-                throw LexerError(.unexpectedToken(String(start[range])), at: range)
+                throw LexerError(.invalidEscapeSequence(String(start[range])), at: range)
             }
             removeFirst()
             escaped = false
diff --git a/ShapeScriptTests/LexerTests.swift b/ShapeScriptTests/LexerTests.swift
@@ -184,7 +184,7 @@ class LexerTests: XCTestCase {
         let range = input.range(of: "\\'")!
         XCTAssertThrowsError(try tokenize(input)) { error in
             let error = try? XCTUnwrap(error as? LexerError)
-            XCTAssertEqual(error, LexerError(.unexpectedToken("\\'"), at: range))
+            XCTAssertEqual(error, LexerError(.invalidEscapeSequence("\\'"), at: range))
         }
     }
 

Original file line number	Diff line number	Diff line change
`@@ -88,6 +88,7 @@ public enum LexerErrorType: Equatable {`
`88`	`88`	`case invalidColor(String)`
`89`	`89`	`case unexpectedToken(String)`
`90`	`90`	`case unterminatedString`
	`91`	`+ case invalidEscapeSequence(String)`
`91`	`92`	`}`
`92`	`93`
`93`	`94`	`public struct LexerError: Error, Equatable {`
`@@ -107,6 +108,11 @@ public struct LexerError: Error, Equatable {`
`107`	`108`	`return "Unexpected token '\(token)'"`
`108`	`109`	`case .unterminatedString:`
`109`	`110`	`return "Unterminated string literal"`
	`111`	`+ case let .invalidEscapeSequence(sequence):`
	`112`	`+ let sequence = sequence.unicodeScalars.contains {`
	`113`	`+ CharacterSet.whitespaces.contains($0)`
	`114`	`+ } ? "'\(sequence)'" : sequence`
	`115`	`+ return "Invalid escape sequence \(sequence)"`
`110`	`116`	`}`
`111`	`117`	`}`
`112`	`118`
`@@ -123,6 +129,8 @@ public struct LexerError: Error, Equatable {`
`123`	`129`	`return nil`
`124`	`130`	`case .unterminatedString:`
`125`	`131`	`return "Try adding a closing \" (double quote) at the end of the line."`
	`132`	`+ case .invalidEscapeSequence:`
	`133`	`+ return "Supported sequences are \\\", \\n and \\\\."`
`126`	`134`	`}`
`127`	`135`	`}`
`128`	`136`
`@@ -337,7 +345,7 @@ private extension Substring {`
`337`	`345`	`break loop`
`338`	`346`	`default:`
`339`	`347`	`let range = start.index(before: startIndex) ..< index(after: startIndex)`
`340`		`- throw LexerError(.unexpectedToken(String(start[range])), at: range)`
	`348`	`+ throw LexerError(.invalidEscapeSequence(String(start[range])), at: range)`
`341`	`349`	`}`
`342`	`350`	`removeFirst()`
`343`	`351`	`escaped = false`
Original file line number	Diff line number	Diff line change
`@@ -184,7 +184,7 @@ class LexerTests: XCTestCase {`
`184`	`184`	`let range = input.range(of: "\\'")!`
`185`	`185`	`XCTAssertThrowsError(try tokenize(input)) { error in`
`186`	`186`	`let error = try? XCTUnwrap(error as? LexerError)`
`187`		`- XCTAssertEqual(error, LexerError(.unexpectedToken("\\'"), at: range))`
	`187`	`+ XCTAssertEqual(error, LexerError(.invalidEscapeSequence("\\'"), at: range))`
`188`	`188`	`}`
`189`	`189`	`}`
`190`	`190`