feat: implement lexer

Merge request lab2425_spring/WACC_37!5

Co-authored-by: Jonny <j.sinteix@gmail.com>

.scalafmt.conf

@@ -1,4 +1,5 @@
 version = 3.8.6
 runner.dialect = scala3
 
+binPack.literalsExclude = []
 maxColumn = 100

src/main/wacc/lexer.scala

@@ -1,16 +1,53 @@
 package wacc
 
 import parsley.Parsley
-import parsley.token.Lexer
+import parsley.token.{Basic, Lexer}
 import parsley.token.descriptions.*
 
 object lexer {
   private val desc = LexicalDesc.plain.copy(
-    // your configuration goes here
+    nameDesc = NameDesc.plain.copy(
+      identifierStart = Basic(c => c.isLetter || c == '_'),
+      identifierLetter = Basic(c => c.isLetterOrDigit || c == '_')
+    ),
+    symbolDesc = SymbolDesc.plain.copy(
+      hardKeywords = Set(
+        "begin", "end", "is", "skip", "if", "then", "else", "fi", "while", "do", "done", "read",
+        "free", "return", "exit", "print", "println", "true", "false", "int", "bool", "char",
+        "string", "pair", "newpair", "fst", "snd", "call", "chr", "ord", "len", "null"
+      ),
+      hardOperators = Set(
+        "+", "-", "*", "/", "%", ">", "<", ">=", "<=", "==", "!=", "&&", "||", "!"
+      )
+    ),
+    spaceDesc = SpaceDesc.plain.copy(
+      lineCommentStart = "#"
+    ),
+    textDesc = TextDesc.plain.copy(
+      graphicCharacter = Basic(c => c >= ' ' && c != '\\' && c != '\'' && c != '"'),
+      escapeSequences = EscapeDesc.plain.copy(
+        literals = Set('\\', '"', '\''),
+        mapping = Map(
+          "0" -> '\u0000',
+          "b" -> '\b',
+          "t" -> '\t',
+          "n" -> '\n',
+          "f" -> '\f',
+          "r" -> '\r'
+        )
+      )
+    ),
+    numericDesc = NumericDesc.plain.copy(
+      decimalExponentDesc = ExponentDesc.NoExponents
+    )
   )
-  private val lexer = Lexer(desc)
 
-  val integer = lexer.lexeme.integer.decimal
+  private val lexer = Lexer(desc)
+  val ident = lexer.lexeme.names.identifier
+  val integer = lexer.lexeme.integer.decimal32[Int]
+  val charLit = lexer.lexeme.character.ascii
+  val stringLit = lexer.lexeme.string.ascii
   val implicits = lexer.lexeme.symbol.implicits
+
   def fully[A](p: Parsley[A]): Parsley[A] = lexer.fully(p)
 }

src/main/wacc/parser.scala

@@ -1,20 +1,8 @@
 package wacc
 
-import parsley.{Parsley, Result}
-import parsley.expr.chain
-
-import lexer.implicits.implicitSymbol
-import lexer.{integer, fully}
+import parsley.Result
 
 object parser {
   def parse(input: String): Result[String, BigInt] = parser.parse(input)
-  private val parser = fully(expr)
-
-  private val add = (x: BigInt, y: BigInt) => x + y
-  private val sub = (x: BigInt, y: BigInt) => x - y
-
-  private lazy val expr: Parsley[BigInt] =
-    chain.left1(integer | "(" ~> expr <~ ")")(
-      ("+" as add) | ("-" as sub)
-    )
+  private val parser = lexer.fully(???)
 }

src/test/wacc/examples.scala

@@ -39,6 +39,8 @@ class ParallelExamplesSpec extends AnyFlatSpec with BeforeAndAfterAll with Paral
 
   def fileIsDissallowed(filename: String): Boolean =
     Seq(
+      // format: off
+      // disable formatting to avoid binPack
       "wacc-examples/valid/advanced",
       "wacc-examples/valid/array",
       "wacc-examples/valid/basic/exit",
@@ -85,5 +87,6 @@ class ParallelExamplesSpec extends AnyFlatSpec with BeforeAndAfterAll with Paral
       "wacc-examples/invalid/semanticErr/while",
       // invalid (whack)
       "wacc-examples/invalid/whack"
+      // format: on
     ).find(filename.contains).isDefined
 }