CustomStringConvertible for Parser errors

Author: milseman

Sources/_MatchingEngine/Regex/Parse/Diagnostics.swift

@@ -26,6 +26,41 @@ enum ParseError: Error, Hashable {
  case emptyProperty
 }
 
+extension ParseError: CustomStringConvertible {
+ var description: String {
+ switch self {
+ case let .numberOverflow(s):
+ return "number overflow: \(s)"
+ case let .expectedNumDigits(s, i):
+ return "expected \(i) digits in '\(s)'"
+ case let .expectedNumber(s, kind: kind):
+ let radix: String
+ if kind == .decimal {
+ radix = ""
+ } else {
+ radix = " of radix \(kind.radix)"
+ }
+ return "expected a numbers in '\(s)'\(radix)"
+ case let .expected(s):
+ return "expected '\(s)'"
+ case .unexpectedEndOfInput:
+ return "unexpected end of input"
+ case let .misc(s):
+ return s
+ case let .expectedASCII(c):
+ return "expected ASCII for '\(c)'"
+ case .expectedCustomCharacterClassMembers:
+ return "expected custom character class members"
+ case .invalidCharacterClassRangeOperand:
+ return "invalid character class range"
+ case let .invalidPOSIXSetName(n):
+ return "invalid character set name: '\(n)'"
+ case .emptyProperty:
+ return "empty property"
+ }
+ }
+}
+
 // TODO: Fixits, notes, etc.
 
 // TODO: Diagnostics engine, recorder, logger, or similar.

Tests/RegexTests/DiagnosticTests.swift

@@ -86,4 +86,12 @@ extension RegexTests {
  // TODO: Find out way to render value-members of AST, not
  // just children
  }
+
+ func testErrors() {
+ // Note: These don't really "test" anything, but good to
+ // see our output...
+ print("\(ParseError.emptyProperty)")
+ print("\(ParseError.expectedNumber("abc", kind: .decimal))")
+ print("\(ParseError.expectedNumber("abc", kind: .hex))")
+ }
 }