Complete Lexer

The last commit says that it finished the lexer, but this was a mistake. The literals still had to be added into the lexer.

So this is "finishing" the lexer. It is not really "finished" as there are some small changes that can be made. (Like better error handling)

Author: QuickWrite

src/main/kotlin/lexer/StringJSONLexer.kt

@@ -23,10 +23,23 @@ class StringJSONLexer(private val content: CharSequence) : JSONLexer {
                 parseNumber(true)
             }
             '"' -> parseString()
-            else -> TODO("Not implemented")
+            't' -> parseLiteral("true", JSONLexemeType.TRUE)
+            'f' -> parseLiteral("false", JSONLexemeType.FALSE)
+            'n' -> parseLiteral("null", JSONLexemeType.NULL)
+            else -> throw LexerException("Invalid token")
         }
     }
 
+    private fun parseLiteral(input: String, type: JSONLexemeType): JSONLexeme {
+        for (i in input) {
+            if(content.getChar(position) != i) {
+                throw LexerException("Expected '$input', but got malformed input")
+            }
+            position++
+        }
+        return JSONLexeme(type)
+    }
+
     private fun charLexeme(type: JSONLexemeType): JSONLexeme {
         position++
         return JSONLexeme(type)
@@ -40,7 +53,7 @@ class StringJSONLexer(private val content: CharSequence) : JSONLexer {
         while (content.getChar(position) != '"' && content.getChar(position) != 0.toChar()) {
             if (content[position] == '\\') {
                 position++
-                builder.append(when(content.getChar(position)) {
+                builder.append(when(val char = content.getChar(position)) {
                     '"' -> '"'
                     '\\' -> '\\'
                     '/' -> '/'
@@ -50,7 +63,7 @@ class StringJSONLexer(private val content: CharSequence) : JSONLexer {
                     'r' -> '\r'
                     't' -> '\t'
                     'u' -> parseUDigitNumber()
-                    else -> TODO()
+                    else -> throw LexerException("The character $char cannot be escaped") // TODO: Better error handling
                 })
                 position++
                 continue

src/test/kotlin/lexer/StringJSONLexerTest.kt

@@ -73,7 +73,7 @@ class StringJSONLexerTest {
     }
 
     @Test
-    fun `simple String test()`() {
+    fun `simple String test`() {
         val inputs = arrayOf("\"\"", "\"Hello World\"")
 
         inputs.forEach {
@@ -86,12 +86,42 @@ class StringJSONLexerTest {
     }
 
     @Test
-    fun `complex String test()`() {
+    fun `complex String test`() {
         val input = "\"\\\" \\\\ \\/ \\b \\f \\n \\r \\t \\u000A\""
 
         assertEquals(
             JSONLexeme(JSONLexemeType.STRING, "\" \\ / \b \u000C \n \r \t \u000A"),
             StringJSONLexer(input).getNext()
         )
     }
+
+    @Test
+    fun `true literal test`() {
+        val input = "true"
+
+        assertEquals(
+            JSONLexeme(JSONLexemeType.TRUE),
+            StringJSONLexer(input).getNext()
+        )
+    }
+
+    @Test
+    fun `false literal test`() {
+        val input = "false"
+
+        assertEquals(
+            JSONLexeme(JSONLexemeType.FALSE),
+            StringJSONLexer(input).getNext()
+        )
+    }
+
+    @Test
+    fun `null literal test`() {
+        val input = "null"
+
+        assertEquals(
+            JSONLexeme(JSONLexemeType.NULL),
+            StringJSONLexer(input).getNext()
+        )
+    }
 }