feat: Support basic expression

.gitignore

@@ -5,6 +5,7 @@
 
 # Build folder
 _build/
+*.opam
 
 # Mac OS
 .DS_Store

.ocamlformat

@@ -0,0 +1,2 @@
+profile = default
+version = 0.26.2

bin/dune

@@ -1,4 +1,6 @@
+;bin/dune
+
 (executable
- (public_name croissant)
  (name main)
- (libraries croissant))
+ (public_name croissant)
+ (libraries parser lexer ast))

bin/main.ml

@@ -1 +1,19 @@
-let () = print_endline "Hello, World!"
+(* bin/main.ml *)
+
+open Printf
+open Ast
+
+let () =
+  let lexbuf = Lexing.from_channel stdin in
+  let res =
+    try Parser.main Lexer.token lexbuf with
+    | Lexer.Error c ->
+        fprintf stderr "Lexical error at line %d: Unknown character '%c'\n"
+          lexbuf.lex_curr_p.pos_lnum c;
+        exit 1
+    | Parser.Error ->
+        fprintf stderr "Parse error at line %d:\n" lexbuf.lex_curr_p.pos_lnum;
+        exit 1
+  in
+  let _ = res in
+  Printf.printf "%s\n" (string_of_source_file res)

dune-project

@@ -1,26 +1,20 @@
-(lang dune 3.10)
+(lang dune 3.4)
 
 (name croissant)
-
 (generate_opam_files true)
-
-(source
- (github username/reponame))
-
-(authors "Author Name")
-
-(maintainers "Maintainer Name")
-
+(source (github LucasVbr/croissant))
+(authors "LucasVbr")
+(maintainers "LucasVbr")
 (license LICENSE)
-
-(documentation https://url/to/documentation)
+;(documentation https://url/to/documentation)
 
 (package
   (name croissant)
   (synopsis "A short synopsis")
   (description "A longer description")
- (depends ocaml dune)
+  (depends ocaml dune alcotest menhir ocamlformat)
   (tags
-  (topics "to describe" your project)))
-
-; See the complete stanza docs at https://dune.readthedocs.io/en/stable/dune-files.html#dune-project
+    ("Custom programming language" "French")
+  )
+)
+(using menhir 2.1)

lib/ast.ml

@@ -0,0 +1,34 @@
+(* lib/ast.ml *)
+
+type binary_operator = Add | Substract | Multiply | Divide
+
+type expression =
+  | IntegerLiteral of int
+  | BinaryExpression of binary_operator * expression * expression
+
+type statement = ExpressionStatement of expression
+type source_file = SourceFile of statement list
+
+(* Print AST *)
+
+let string_of_binary_operator = function
+  | Add -> "Add"
+  | Substract -> "Substract"
+  | Multiply -> "Multiply"
+  | Divide -> "Divide"
+
+let rec string_of_expression = function
+  | IntegerLiteral i -> "IntegerLiteral(" ^ string_of_int i ^ ")"
+  | BinaryExpression (op, e1, e2) ->
+      "BinaryExpression("
+      ^ string_of_binary_operator op
+      ^ ", " ^ string_of_expression e1 ^ ", " ^ string_of_expression e2 ^ ")"
+
+let string_of_statement = function
+  | ExpressionStatement e ->
+      "ExpressionStatement(" ^ string_of_expression e ^ ")"
+
+let string_of_source_file = function
+  | SourceFile stmts ->
+      let stmt_strings = List.map string_of_statement stmts in
+      "SourceFile([" ^ String.concat ", " stmt_strings ^ "])"

lib/dune

@@ -1,2 +1,21 @@
+;lib/dune
+
 (library
- (name croissant))
+ (name lexer)
+ (modules lexer)
+ (libraries parser))
+
+(library
+ (name parser)
+ (modules parser)
+ (libraries ast))
+
+(library
+ (name ast)
+ (modules ast))
+
+(menhir
+ (modules parser))
+
+(ocamllex
+ (modules lexer))

lib/lexer.mll

@@ -0,0 +1,28 @@
+(* lib/lexer.mll *)
+{
+  open Parser
+  exception Error of char
+}
+
+let line_comment = "//" [^ '\n']*
+
+let digit = ['0'-'9']
+let integer = digit+
+
+rule token = parse
+   |  [' ' '\t'] | line_comment { token lexbuf }
+   | ['\n'] { Lexing.new_line lexbuf; token lexbuf }
+
+   | '+' { PLUS }
+   | '-' { MINUS }
+   | '*' { TIMES }
+   | '/' { DIVIDE }
+   | ';' { SEMICOLON }
+
+   | integer as lxm { INT(int_of_string lxm) }
+
+   | '(' { LPAREN }
+   | ')' { RPAREN }
+
+   | eof { EOF }
+   | _ as c { raise (Error c) }

lib/parser.mly

@@ -0,0 +1,51 @@
+/* lib/parser.mly */
+%{
+   open Ast
+%}
+
+%token <int> INT
+
+%token PLUS "+"
+%token MINUS "-"
+%token TIMES "*"
+%token DIVIDE "/"
+
+%token LPAREN "("
+%token RPAREN ")"
+
+%token SEMICOLON ";"
+
+%token EOF
+
+%left "+" "-"
+%left "*" "/"
+//%nonassoc UMINUS
+
+%start main
+%type <source_file> main
+
+%%
+
+main:
+  | statements EOF { SourceFile($1) }
+
+statements:
+  | statement ";" { [$1] }
+  | statement ";" statements { $1 :: $3 }
+
+statement:
+  | expression { ExpressionStatement($1) }
+
+expression:
+  | literal { $1 }
+  | binary_expression { $1 }
+  | "(" expression ")" { $2 }
+
+literal:
+  | INT { IntegerLiteral($1) }
+
+binary_expression:
+  | e1=expression PLUS e2=expression { BinaryExpression(Add, e1, e2) }
+  | e1=expression MINUS e2=expression { BinaryExpression(Substract, e1, e2) }
+  | e1=expression TIMES e2=expression { BinaryExpression(Multiply, e1, e2) }
+  | e1=expression DIVIDE e2=expression { BinaryExpression(Divide, e1, e2) }

test/ast.ml

@@ -0,0 +1,54 @@
+(* test/ast.ml *)
+
+open Alcotest
+open Ast
+
+let test_string_of_binary_operator () =
+  check string "+" "Add" (string_of_binary_operator Add);
+  check string "-" "Substract" (string_of_binary_operator Substract);
+  check string "*" "Multiply" (string_of_binary_operator Multiply);
+  check string "/" "Divide" (string_of_binary_operator Divide)
+
+let test_string_of_expression () =
+  let expr = BinaryExpression (Add, IntegerLiteral 1, IntegerLiteral 2) in
+  check string "1 + 2"
+    "BinaryExpression(Add, IntegerLiteral(1), IntegerLiteral(2))"
+    (string_of_expression expr)
+
+let test_string_of_statement () =
+  let stmt = ExpressionStatement (IntegerLiteral 42) in
+  check string "42;" "ExpressionStatement(IntegerLiteral(42))"
+    (string_of_statement stmt)
+
+let test_string_of_source_file () =
+  let source_file =
+    SourceFile
+      [
+        ExpressionStatement (IntegerLiteral 1);
+        ExpressionStatement
+          (BinaryExpression (Add, IntegerLiteral 2, IntegerLiteral 3));
+      ]
+  in
+  check string "1; 2 + 3;"
+    "SourceFile([ExpressionStatement(IntegerLiteral(1)), \
+     ExpressionStatement(BinaryExpression(Add, IntegerLiteral(2), \
+     IntegerLiteral(3)))])"
+    (string_of_source_file source_file)
+
+let () =
+  let open Alcotest in
+  run "AST tests"
+    [
+      ( "string_of_binary_operator",
+        [
+          test_case "string_of_binary_operator" `Quick
+            test_string_of_binary_operator;
+        ] );
+      ( "string_of_expression",
+        [ test_case "string_of_expression" `Quick test_string_of_expression ] );
+      ( "string_of_statement",
+        [ test_case "string_of_statement" `Quick test_string_of_statement ] );
+      ( "string_of_source_file",
+        [ test_case "string_of_source_file" `Quick test_string_of_source_file ]
+      );
+    ]

test/dune

@@ -1,2 +1,5 @@
+;test/dune
+
 (test
- (name croissant))
+ (name ast)
+ (libraries ast alcotest))