Adds support for case insensitivity (#168)

Author: natecook1000

Sources/_StringProcessing/ByteCodeGen.swift

@@ -20,15 +20,11 @@ extension Compiler.ByteCodeGen {
       emitAny()
 
     case let .char(c):
-      // FIXME: Does semantic level matter?
-      builder.buildMatch(c)
-
+      try emitCharacter(c)
+      
     case let .scalar(s):
-      // TODO: Native instruction
-      builder.buildConsume(by: consumeScalar {
-        $0 == s
-      })
-
+      try emitScalar(s)
+      
     case let .assertion(kind):
       try emitAssertion(kind)
 
@@ -135,6 +131,36 @@ extension Compiler.ByteCodeGen {
       }
     }
   }
+  
+  mutating func emitScalar(_ s: UnicodeScalar) throws {
+    // TODO: Native instruction buildMatchScalar(s)
+    if options.isCaseInsensitive {
+      // TODO: e.g. buildCaseInsensitiveMatchScalar(s)
+      builder.buildConsume(by: consumeScalar {
+        $0.properties.lowercaseMapping == s.properties.lowercaseMapping
+      })
+    } else {
+      builder.buildConsume(by: consumeScalar {
+        $0 == s
+      })
+    }
+  }
+  
+  mutating func emitCharacter(_ c: Character) throws {
+    // FIXME: Does semantic level matter?
+    if options.isCaseInsensitive && c.isCased {
+      // TODO: buildCaseInsensitiveMatch(c) or buildMatch(c, caseInsensitive: true)
+      builder.buildConsume { input, bounds in
+        let inputChar = input[bounds.lowerBound].lowercased()
+        let matchChar = c.lowercased()
+        return inputChar == matchChar
+          ? input.index(after: bounds.lowerBound)
+          : nil
+      }
+    } else {
+      builder.buildMatch(c)
+    }
+  }
 
   mutating func emitAny() {
     switch (options.semanticLevel, options.dotMatchesNewline) {
@@ -543,7 +569,22 @@ extension Compiler.ByteCodeGen {
 
     case let .quotedLiteral(s):
       // TODO: Should this incorporate options?
-      builder.buildMatchSequence(s)
+      if options.isCaseInsensitive {
+        // TODO: buildCaseInsensitiveMatchSequence(c) or alternative
+        builder.buildConsume { input, bounds in
+          var iterator = s.makeIterator()
+          var currentIndex = bounds.lowerBound
+          while let ch = iterator.next() {
+            guard currentIndex < bounds.upperBound,
+                  ch.lowercased() == input[currentIndex].lowercased()
+            else { return nil }
+            input.formIndex(after: &currentIndex)
+          }
+          return currentIndex
+        }
+      } else {
+        builder.buildMatchSequence(s)
+      }
 
     case let .regexLiteral(l):
       try emitNode(l.dslTreeNode)

Sources/_StringProcessing/ConsumerInterface.swift

@@ -51,24 +51,34 @@ extension DSLTree.Node {
 }
 
 extension DSLTree.Atom {
-  // TODO: If ByteCodeGen switches first, then this is
-  // unnecessary...
+  // TODO: If ByteCodeGen switches first, then this is unnecessary for
+  // top-level nodes, but it's also invoked for `.atom` members of a custom CC
   func generateConsumer(
     _ opts: MatchingOptions
   ) throws -> MEProgram<String>.ConsumeFunction? {
+    let isCaseInsensitive = opts.isCaseInsensitive
+    
     switch self {
-
     case let .char(c):
       // TODO: Match level?
       return { input, bounds in
         let low = bounds.lowerBound
-        guard input[low] == c else {
-          return nil
+        if isCaseInsensitive && c.isCased {
+          return input[low].lowercased() == c.lowercased()
+            ? input.index(after: low)
+            : nil
+        } else {
+          return input[low] == c
+            ? input.index(after: low)
+            : nil
         }
-        return input.index(after: low)
       }
     case let .scalar(s):
-      return consumeScalar { $0 == s }
+      return consumeScalar {
+        isCaseInsensitive
+          ? $0.properties.lowercaseMapping == s.properties.lowercaseMapping
+          : $0 == s
+      }
 
     case .any:
       // FIXME: Should this be a total ordering?
@@ -187,14 +197,30 @@ extension DSLTree.CustomCharacterClass.Member {
         throw Unsupported("\(high) in range")
       }
 
-      return { input, bounds in
-        // TODO: check for out of bounds?
-        let curIdx = bounds.lowerBound
-        if (lhs...rhs).contains(input[curIdx]) {
-          // TODO: semantic level
-          return input.index(after: curIdx)
+      if opts.isCaseInsensitive {
+        let lhsLower = lhs.lowercased()
+        let rhsLower = rhs.lowercased()
+        guard lhsLower <= rhsLower else { throw Unsupported("Invalid range \(lhs)-\(rhs)") }
+        return { input, bounds in
+          // TODO: check for out of bounds?
+          let curIdx = bounds.lowerBound
+          if (lhsLower...rhsLower).contains(input[curIdx].lowercased()) {
+            // TODO: semantic level
+            return input.index(after: curIdx)
+          }
+          return nil
+        }
+      } else {
+        guard lhs <= rhs else { throw Unsupported("Invalid range \(lhs)-\(rhs)") }
+        return { input, bounds in
+          // TODO: check for out of bounds?
+          let curIdx = bounds.lowerBound
+          if (lhs...rhs).contains(input[curIdx]) {
+            // TODO: semantic level
+            return input.index(after: curIdx)
+          }
+          return nil
         }
-        return nil
       }
 
     case let .custom(ccc):
@@ -237,11 +263,20 @@ extension DSLTree.CustomCharacterClass.Member {
         return rhs(input, bounds)
       }
     case .quotedLiteral(let s):
-      return { input, bounds in
-        guard s.contains(input[bounds.lowerBound]) else {
-          return nil
+      if opts.isCaseInsensitive {
+        return { input, bounds in
+          guard s.lowercased().contains(input[bounds.lowerBound].lowercased()) else {
+            return nil
+          }
+          return input.index(after: bounds.lowerBound)
+        }
+      } else {
+        return { input, bounds in
+          guard s.contains(input[bounds.lowerBound]) else {
+            return nil
+          }
+          return input.index(after: bounds.lowerBound)
         }
-        return input.index(after: bounds.lowerBound)
       }
     case .trivia:
       // TODO: Should probably strip this earlier...

Sources/_StringProcessing/MatchingOptions.swift

@@ -25,7 +25,7 @@ struct MatchingOptions {
   }
 }
 
-// Compiler API
+// MARK: Compilation API
 extension MatchingOptions {
   /// Creates an instance with the default options.
   init() {
@@ -51,7 +51,14 @@ extension MatchingOptions {
     stack[stack.count - 1].apply(sequence)
     _invariantCheck()
   }
+}
 
+// MARK: Matching behavior API
+extension MatchingOptions {
+  var isCaseInsensitive: Bool {
+    stack.last!.contains(.caseInsensitive)
+  }
+  
   var isReluctantByDefault: Bool {
     stack.last!.contains(.reluctantByDefault)
   }

Tests/RegexTests/MatchTests.swift

@@ -115,7 +115,9 @@ func matchTest(
   syntax: SyntaxOptions = .traditional,
   enableTracing: Bool = false,
   dumpAST: Bool = false,
-  xfail: Bool = false
+  xfail: Bool = false,
+  file: StaticString = #file,
+  line: UInt = #line
 ) {
   for (test, expect) in tests {
     firstMatchTest(
@@ -125,7 +127,9 @@ func matchTest(
       syntax: syntax,
       enableTracing: enableTracing,
       dumpAST: dumpAST,
-      xfail: xfail)
+      xfail: xfail,
+      file: file,
+      line: line)
   }
 }
 
@@ -1126,6 +1130,43 @@ extension RegexTests {
     firstMatchTest(#"(?s:.+)"#, input: "a\nb", match: "a\nb")
   }
 
+  func testCaseSensitivity() {
+    matchTest(
+      #"c..e"#,
+      ("cafe", true),
+      ("Cafe", false))
+    matchTest(
+      #"(?i)c.f."#,
+      ("cafe", true),
+      ("Cafe", true),
+      ("caFe", true))
+    matchTest(
+      #"(?i)cafe"#,
+      ("cafe", true),
+      ("Cafe", true),
+      ("caFe", true))
+    matchTest(
+      #"(?i)café"#,
+      ("café", true),
+      ("CafÉ", true))
+    matchTest(
+      #"(?i)\u{63}af\u{e9}"#,
+      ("café", true),
+      ("CafÉ", true))
+    
+    matchTest(
+      #"[caFE]{4}"#,
+      ("cafe", false),
+      ("CAFE", false),
+      ("caFE", true),
+      ("EFac", true))
+    matchTest(
+      #"(?i)[caFE]{4}"#,
+      ("cafe", true),
+      ("CaFe", true),
+      ("EfAc", true))
+  }
+  
   func testMatchingOptionsScope() {
     // `.` only matches newlines when the 's' option (single-line mode)
     // is turned on. Standalone option-setting groups (e.g. `(?s)`) are