Merge pull request #587 from Azoy/lookahead-convert

Print Lookahead and NegativeLookahead

Author: Azoy

Sources/_StringProcessing/PrintAsPattern.swift

@@ -119,6 +119,16 @@ extension PrettyPrinter {
           printer.printAsPattern(convertedFromAST: child)
         }
 
+      case .lookahead:
+        printBlock("Lookahead") { printer in
+          printer.printAsPattern(convertedFromAST: child)
+        }
+        
+      case .negativeLookahead:
+        printBlock("NegativeLookahead") { printer in
+          printer.printAsPattern(convertedFromAST: child)
+        }
+        
       default:
         printAsPattern(convertedFromAST: child)
       }

Tests/RegexTests/RenderDSLTests.swift

@@ -98,6 +98,32 @@ extension RenderDSLTests {
         /$/
       }
       """#)
+    
+    try testConversion(#"foo(?=bar)"#, #"""
+      Regex {
+        "foo"
+        Lookahead {
+          "bar"
+        }
+      }
+      """#)
+    
+    try testConversion(#"abc(?=def(?!ghi)|xyz)"#, #"""
+      Regex {
+        "abc"
+        Lookahead {
+          ChoiceOf {
+            Regex {
+              "def"
+              NegativeLookahead {
+                "ghi"
+              }
+            }
+            "xyz"
+          }
+        }
+      }
+      """#)
   }
 
   func testOptions() throws {