Strip comments

Author: lujjjh

Sources/JSONPatcher/JSONCParser.swift

@@ -1,13 +1,18 @@
 class JSONCParser {
     private let scanner: JSONCScanner
+    private(set) var comments: [Token] = []
 
-    init(jsoncString: String) throws {
+    init(jsoncString: String) {
         scanner = .init(jsoncString: jsoncString)
     }
 
     func parse() throws -> Value {
         try scanNext()
-        return try parseValue()
+        let value = try parseValue()
+        guard scanner.token.kind == .eof else {
+            throw ParsingError.eofExpected(loc: scanner.token.loc)
+        }
+        return value
     }
 
     @discardableResult
@@ -16,6 +21,7 @@ class JSONCParser {
             let token = try scanner.scanToken()
             switch token.kind {
             case .lineComment, .blockComment:
+                comments.append(token)
                 break
             default:
                 return token

Sources/JSONPatcher/JSONPatcher.swift

@@ -0,0 +1,22 @@
+public class JSONPatcher {
+    private let parser: JSONCParser
+    private let original: String
+    private let originalValue: JSONCParser.Value
+
+    init(original: String) throws {
+        self.parser = JSONCParser(jsoncString: original)
+        self.original = original
+        originalValue = try parser.parse()
+    }
+
+    /**
+     Strips comments and returns valid JSON.
+     */
+    func json() -> String {
+        var stripped = original
+        for token in parser.comments.reversed() {
+            stripped.removeSubrange(token.loc)
+        }
+        return stripped
+    }
+}

Sources/JSONPatcher/Scanner.swift

@@ -69,4 +69,5 @@ enum ParsingError: Error {
     case colonExpected(loc: Loc)
     case rightBraceExpected(loc: Loc)
     case rightBracketExpected(loc: Loc)
+    case eofExpected(loc: Loc)
 }

Tests/JSONPatcherTests/JSONPatcherTests.swift

@@ -0,0 +1,13 @@
+@testable import JSONPatcher
+import XCTest
+
+final class JSONPatcherTests: XCTestCase {
+    override func setUp() {
+        continueAfterFailure = false
+    }
+
+    func testStripComments() throws {
+        let patcher = try JSONPatcher(original: "//comment\n[1, 42.0, /*\"Hello\", */\"World\"\n\t]")
+        XCTAssertEqual(patcher.json(), "\n[1, 42.0, \"World\"\n\t]")
+    }
+}