Add match statement (#621)

bootstrap_compiler/build_cfg.c

@@ -865,6 +865,33 @@ static void build_loop(
     add_jump(st, NULL, condblock, condblock, doneblock);
 }
 
+static void build_match_statament(struct State *st, const AstMatchStatement *match_stmt)
+{
+    const LocalVariable *match_obj_enum = build_expression(st, &match_stmt->match_obj);
+    LocalVariable *match_obj_int = add_local_var(st, intType);
+    add_unary_op(st, match_stmt->match_obj.location, CF_ENUM_TO_INT32, match_obj_enum, match_obj_int);
+
+    CfBlock *done = add_block(st);
+    for (int i = 0; i < match_stmt->ncases; i++) {
+    for (AstExpression *caseobj = match_stmt->cases[i].case_objs; caseobj < &match_stmt->cases[i].case_objs[match_stmt->cases[i].n_case_objs]; caseobj++) {
+        const LocalVariable *case_obj_enum = build_expression(st, caseobj);
+        LocalVariable *case_obj_int = add_local_var(st, intType);
+        add_unary_op(st, caseobj->location, CF_ENUM_TO_INT32, case_obj_enum, case_obj_int);
+
+        const LocalVariable *cond = build_binop(st, AST_EXPR_EQ, caseobj->location, match_obj_int, case_obj_int, boolType);
+        CfBlock *then = add_block(st);
+        CfBlock *otherwise = add_block(st);
+
+        add_jump(st, cond, then, otherwise, then);
+        build_body(st, &match_stmt->cases[i].body);
+        add_jump(st, NULL, done, done, otherwise);
+    }
+    }
+
+    build_body(st, &match_stmt->case_underscore);
+    add_jump(st, NULL, done, done, done);
+}
+
 static void build_statement(struct State *st, const AstStatement *stmt)
 {
     switch(stmt->kind) {
@@ -891,6 +918,10 @@ static void build_statement(struct State *st, const AstStatement *stmt)
             &stmt->data.forloop.body);
         break;
 
+    case AST_STMT_MATCH:
+        build_match_statament(st, &stmt->data.match);
+        break;
+
     case AST_STMT_BREAK:
         if (!st->breakstack.len)
             fail(stmt->location, "'break' can only be used inside a loop");

bootstrap_compiler/free.c

@@ -155,6 +155,18 @@ void free_ast_statement(const AstStatement *stmt)
         free(stmt->data.forloop.incr);
         free_ast_body(&stmt->data.forloop.body);
         break;
+    case AST_STMT_MATCH:
+        free_expression(&stmt->data.match.match_obj);
+        for (int i = 0; i < stmt->data.match.ncases; i++) {
+            for (AstExpression *caseobj = stmt->data.match.cases[i].case_objs; caseobj < &stmt->data.match.cases[i].case_objs[stmt->data.match.cases[i].n_case_objs]; caseobj++) {
+                free_expression(caseobj);
+            }
+            free(stmt->data.match.cases[i].case_objs);
+            free_ast_body(&stmt->data.match.cases[i].body);
+        }
+        free(stmt->data.match.cases);
+        free_ast_body(&stmt->data.match.case_underscore);
+        break;
     case AST_STMT_ASSERT:
         free_expression(&stmt->data.assertion.condition);
         free(stmt->data.assertion.condition_str);

bootstrap_compiler/jou_compiler.h

@@ -23,6 +23,8 @@ typedef struct AstConditionAndBody AstConditionAndBody;
 typedef struct AstExpression AstExpression;
 typedef struct AstAssignment AstAssignment;
 typedef struct AstForLoop AstForLoop;
+typedef struct AstCase AstCase;
+typedef struct AstMatchStatement AstMatchStatement;
 typedef struct AstNameTypeValue AstNameTypeValue;
 typedef struct AstIfStatement AstIfStatement;
 typedef struct AstStatement AstStatement;
@@ -264,6 +266,17 @@ struct AstForLoop {
     AstStatement *incr;
     AstBody body;
 };
+struct AstCase {
+    AstExpression *case_objs;
+    int n_case_objs;
+    AstBody body;
+};
+struct AstMatchStatement {
+    AstExpression match_obj;
+    AstCase *cases;
+    int ncases;
+    AstBody case_underscore;
+};
 struct AstIfStatement {
     AstConditionAndBody *if_and_elifs;
     int n_if_and_elifs;  // Always >= 1 for the initial "if"
@@ -327,6 +340,7 @@ struct AstStatement {
         AST_STMT_IF,
         AST_STMT_WHILE,
         AST_STMT_FOR,
+        AST_STMT_MATCH,
         AST_STMT_BREAK,
         AST_STMT_CONTINUE,
         AST_STMT_DECLARE_LOCAL_VAR,
@@ -350,6 +364,7 @@ struct AstStatement {
         AstConditionAndBody whileloop;
         AstIfStatement ifstatement;
         AstForLoop forloop;
+        AstMatchStatement match;
         AstNameTypeValue vardecl;
         AstAssignment assignment;  // also used for inplace operations
         AstFunction function;

bootstrap_compiler/parse.c

@@ -674,6 +674,7 @@ static void validate_expression_statement(const AstExpression *expr)
     }
 }
 
+static void parse_start_of_body(ParserState *ps);
 static AstBody parse_body(ParserState *ps);
 
 static AstIfStatement parse_if_statement(ParserState *ps)
@@ -701,6 +702,49 @@ static AstIfStatement parse_if_statement(ParserState *ps)
     };
 }
 
+static AstMatchStatement parse_match_statement(ParserState *ps)
+{
+    assert(is_keyword(ps->tokens, "match"));
+    ps->tokens++;
+
+    AstMatchStatement result = {.match_obj = parse_expression(ps)};
+    parse_start_of_body(ps);
+
+    while (ps->tokens->type != TOKEN_DEDENT) {
+        assert(is_keyword(ps->tokens, "case"));
+        ps->tokens++;
+
+        if (ps->tokens->type == TOKEN_NAME
+            && strcmp(ps->tokens->data.name, "_") == 0
+            && is_operator(&ps->tokens[1], ":"))
+        {
+            // case _:
+            ps->tokens++;
+            result.case_underscore = parse_body(ps);
+        } else {
+            List(AstExpression) case_objs = {0};
+            while(1){
+                Append(&case_objs, parse_expression(ps));
+                if (is_operator(ps->tokens, "|"))
+                    ps->tokens++;
+                else if (is_operator(ps->tokens, ":"))
+                    break;
+                else
+                    fail_with_parse_error(ps->tokens, "'|' or ':'");
+            }
+            result.cases = realloc(result.cases, sizeof result.cases[0] * (result.ncases + 1));
+            result.cases[result.ncases++] = (AstCase){
+                .case_objs = case_objs.ptr,
+                .n_case_objs = case_objs.len,
+                .body = parse_body(ps),
+            };
+        }
+    }
+    ps->tokens++;
+    return result;
+}
+
+
 // reverse code golfing: https://xkcd.com/1960/
 static enum AstStatementKind determine_the_kind_of_a_statement_that_starts_with_an_expression(
     const Token *this_token_is_after_that_initial_expression)
@@ -1041,6 +1085,9 @@ static AstStatement parse_statement(ParserState *ps)
     } else if (is_keyword(ps->tokens, "if")) {
         result.kind = AST_STMT_IF;
         result.data.ifstatement = parse_if_statement(ps);
+    } else if (is_keyword(ps->tokens, "match")) {
+        result.kind = AST_STMT_MATCH;
+        result.data.match = parse_match_statement(ps);
     } else if (is_keyword(ps->tokens, "while")) {
         ps->tokens++;
         result.kind = AST_STMT_WHILE;

bootstrap_compiler/print.c

@@ -364,6 +364,10 @@ static void print_ast_statement(const AstStatement *stmt, struct TreePrinter tp)
             printf("body:\n");
             print_ast_body(&stmt->data.forloop.body, sub);
             break;
+        case AST_STMT_MATCH:
+            printf("match (printing not implemented)\n");
+            // TODO: implement printing match statement, if needed for debugging
+            break;
         case AST_STMT_BREAK:
             printf("break\n");
             break;

bootstrap_compiler/tokenize.c

@@ -222,7 +222,7 @@ static bool is_keyword(const char *s)
         "return", "if", "elif", "else", "while", "for", "pass", "break", "continue",
         "True", "False", "None", "NULL", "void", "noreturn",
         "and", "or", "not", "self", "as", "sizeof", "assert",
-        "bool", "byte", "short", "int", "long", "float", "double",
+        "bool", "byte", "short", "int", "long", "float", "double", "match", "case",
     };
     for (const char **kw = &keywords[0]; kw < &keywords[sizeof(keywords)/sizeof(keywords[0])]; kw++)
         if (!strcmp(*kw, s))
@@ -351,7 +351,7 @@ static const char *read_operator(struct State *st)
         // Longer operators are first, so that '==' does not tokenize as '=' '='
         "...", "===", "!==",
         "==", "!=", "->", "<=", ">=", "++", "--", "+=", "-=", "*=", "/=", "%=", "&&", "||",
-        ".", ",", ":", ";", "=", "(", ")", "{", "}", "[", "]", "&", "%", "*", "/", "+", "-", "<", ">", "!",
+        ".", ",", ":", ";", "=", "(", ")", "{", "}", "[", "]", "&", "%", "*", "/", "+", "-", "<", ">", "!", "|",
         NULL,
     };
 

bootstrap_compiler/typecheck.c

@@ -794,7 +794,6 @@ static const Type *check_increment_or_decrement(FileTypes *ft, const AstExpressi
 
 static void typecheck_dereferenced_pointer(Location location, const Type *t)
 {
-    // TODO: improved error message for dereferencing void*
     if (t->kind != TYPE_POINTER)
         fail(location, "the dereference operator '*' is only for pointers, not for %s", t->name);
 }
@@ -1287,6 +1286,23 @@ static void typecheck_if_statement(FileTypes *ft, const AstIfStatement *ifstmt)
     typecheck_body(ft, &ifstmt->elsebody);
 }
 
+static void typecheck_match_statement(FileTypes *ft, AstMatchStatement *match_stmt)
+{
+    const Type *mtype = typecheck_expression_not_void(ft, &match_stmt->match_obj)->type;
+    assert(mtype->kind == TYPE_ENUM);
+
+    for (int i = 0; i < match_stmt->ncases; i++) {
+        for (int k = 0; k < match_stmt->cases[i].n_case_objs; k++) {
+            typecheck_expression_with_implicit_cast(
+                ft, &match_stmt->cases[i].case_objs[k], mtype,
+                "case value of type FROM cannot be matched against TO"
+            );
+        }
+        typecheck_body(ft, &match_stmt->cases[i].body);
+    }
+    typecheck_body(ft, &match_stmt->case_underscore);
+}
+
 static void typecheck_statement(FileTypes *ft, AstStatement *stmt)
 {
     switch(stmt->kind) {
@@ -1310,6 +1326,10 @@ static void typecheck_statement(FileTypes *ft, AstStatement *stmt)
         typecheck_statement(ft, stmt->data.forloop.incr);
         break;
 
+    case AST_STMT_MATCH:
+        typecheck_match_statement(ft, &stmt->data.match);
+        break;
+
     case AST_STMT_BREAK:
         break;
 

compiler/ast.jou

@@ -482,6 +482,7 @@ enum AstStatementKind:
     Pass
     Return
     If
+    Match
     WhileLoop
     ForLoop
     Break
@@ -515,6 +516,7 @@ class AstStatement:
         classdef: AstClassDef
         enumdef: AstEnumDef
         assertion: AstAssertion
+        match_statement: AstMatchStatement
 
     def print(self) -> None:
         self->print_with_tree_printer(TreePrinter{})
@@ -537,6 +539,8 @@ class AstStatement:
             self->if_statement.print_with_tree_printer(tp)
         elif self->kind == AstStatementKind.ForLoop:
             self->for_loop.print_with_tree_printer(tp)
+        elif self->kind == AstStatementKind.Match:
+            self->match_statement.print_with_tree_printer(tp)
         elif self->kind == AstStatementKind.WhileLoop:
             printf("while loop\n")
             self->while_loop.print_with_tree_printer(tp, True)
@@ -601,6 +605,8 @@ class AstStatement:
             self->while_loop.free()
         if self->kind == AstStatementKind.ForLoop:
             self->for_loop.free()
+        if self->kind == AstStatementKind.Match:
+            self->match_statement.free()
         if (
             self->kind == AstStatementKind.DeclareLocalVar
             or self->kind == AstStatementKind.GlobalVariableDeclaration
@@ -696,6 +702,62 @@ class AstIfStatement:
         self->else_body.free()
 
 
+# match match_obj:
+#     case ...:
+#         ...
+#     case ...:
+#         ...
+class AstMatchStatement:
+    match_obj: AstExpression
+    cases: AstCase*
+    ncases: int
+    case_underscore: AstBody*  # body of "case _" (always last), NULL if no "case _"
+    case_underscore_location: Location  # not meaningful if case_underscore == NULL
+
+    def print_with_tree_printer(self, tp: TreePrinter) -> None:
+        printf("match\n")
+        for i = 0; i < self->ncases; i++:
+            self->cases[i].print_with_tree_printer(tp, i == self->ncases - 1 and self->case_underscore == NULL)
+
+        if self->case_underscore != NULL:
+            sub = tp.print_prefix(True)
+            printf("[line %d] body of case _:\n", self->case_underscore_location.lineno)
+            self->case_underscore->print_with_tree_printer(sub)
+
+    def free(self) -> None:
+        self->match_obj.free()
+        for i = 0; i < self->ncases; i++:
+            self->cases[i].free()
+        free(self->cases)
+        if self->case_underscore != NULL:
+            self->case_underscore->free()
+            free(self->case_underscore)
+
+
+# case case_obj1 | case_obj2 | case_obj3:
+#     body
+class AstCase:
+    case_objs: AstExpression*
+    n_case_objs: int
+    body: AstBody
+
+    def print_with_tree_printer(self, tp: TreePrinter, is_last_case: bool) -> None:
+        for i = 0; i < self->n_case_objs; i++:
+            sub = tp.print_prefix(False)
+            printf("case_obj: ")
+            self->case_objs[i].print_with_tree_printer(sub)
+
+        sub = tp.print_prefix(is_last_case)
+        printf("body:\n")
+        self->body.print_with_tree_printer(sub)
+
+    def free(self) -> None:
+        for i = 0; i < self->n_case_objs; i++:
+            self->case_objs[i].free()
+        free(self->case_objs)
+        self->body.free()
+
+
 # for init; cond; incr:
 #     ...body...
 class AstForLoop: