[PATCH olang v2 2/4] parser: parse a simple if statement

[Johnny Richard <johnny@johnnyrichard.com>]

From: Carlos Maniero <carlos@maniero.me>

There is no support for else-branch at this point.

Signed-off-by: Carlos Maniero <carlos@maniero.me>
---
 src/ast.c                                    | 13 ++++
 src/ast.h                                    | 11 +++
 src/parser.c                                 | 79 +++++++++++++++++++-
 src/pretty_print_ast.c                       | 14 ++++
 tests/integration/tests/0020_if_statement.ol | 15 ++++
 5 files changed, 128 insertions(+), 4 deletions(-)

diff --git a/src/ast.c b/src/ast.c
index aa9e6db..c1fb6f5 100644
--- a/src/ast.c
+++ b/src/ast.c
@@ -90,6 +90,19 @@ ast_new_node_return_stmt(arena_t *arena)
     return node_return_stmt;
 }
 
+ast_node_t *
+ast_new_node_if_stmt(arena_t *arena, ast_node_t *cond, ast_node_t *then)
+{
+    ast_node_t *node_if_stmt = arena_alloc(arena, sizeof(ast_node_t));
+    assert(node_if_stmt);
+
+    node_if_stmt->kind = AST_NODE_IF_STMT;
+    node_if_stmt->as_if_stmt.cond = cond;
+    node_if_stmt->as_if_stmt.then = then;
+
+    return node_if_stmt;
+}
+
 ast_node_t *
 ast_new_node_block(arena_t *arena)
 {
diff --git a/src/ast.h b/src/ast.h
index 024f2cc..15260c5 100644
--- a/src/ast.h
+++ b/src/ast.h
@@ -32,6 +32,7 @@ typedef enum
     AST_NODE_FN_DEF,
     AST_NODE_BINARY_OP,
     AST_NODE_RETURN_STMT,
+    AST_NODE_IF_STMT,
     AST_NODE_LITERAL,
     AST_NODE_UNKNOWN
 } ast_node_kind_t;
@@ -106,6 +107,12 @@ typedef struct ast_return_stmt
     ast_node_t *data;
 } ast_return_stmt_t;
 
+typedef struct ast_if_stmt
+{
+    ast_node_t *cond;
+    ast_node_t *then;
+} ast_if_stmt_t;
+
 typedef struct ast_node
 {
     ast_node_kind_t kind;
@@ -117,6 +124,7 @@ typedef struct ast_node
         ast_literal_t as_literal;
         ast_block_t as_block;
         ast_return_stmt_t as_return_stmt;
+        ast_if_stmt_t as_if_stmt;
     };
 } ast_node_t;
 
@@ -135,6 +143,9 @@ ast_new_node_literal_u32(arena_t *arena, uint32_t value);
 ast_node_t *
 ast_new_node_return_stmt(arena_t *arena);
 
+ast_node_t *
+ast_new_node_if_stmt(arena_t *arena, ast_node_t *cond, ast_node_t *then);
+
 ast_node_t *
 ast_new_node_block(arena_t *arena);
 
diff --git a/src/parser.c b/src/parser.c
index 24094b3..c0ef977 100644
--- a/src/parser.c
+++ b/src/parser.c
@@ -36,6 +36,12 @@ parser_parse_type(parser_t *parser, type_t *type);
 static ast_node_t *
 parser_parse_block(parser_t *parser);
 
+static ast_node_t *
+parser_parse_return_stmt(parser_t *parser);
+
+static ast_node_t *
+parser_parse_if_stmt(parser_t *parser);
+
 ast_node_t *
 parser_parse_fn_definition(parser_t *parser);
 
@@ -324,6 +330,46 @@ parser_parse_block(parser_t *parser)
         return NULL;
     }
 
+    token_t next_token;
+
+StartLoop:
+    lexer_peek_next(parser->lexer, &next_token);
+    ast_node_t *node = NULL;
+
+    switch (next_token.kind) {
+        case TOKEN_RETURN: {
+            node = parser_parse_return_stmt(parser);
+            break;
+        }
+        case TOKEN_IF: {
+            node = parser_parse_if_stmt(parser);
+            break;
+        }
+        default: {
+            goto EndLoop;
+        }
+    }
+
+    if (node == NULL) {
+        return NULL;
+    }
+
+    list_append(node_block->as_block.nodes, node);
+
+    goto StartLoop;
+EndLoop:
+
+    skip_line_feeds(parser->lexer);
+    if (!skip_expected_token(parser, TOKEN_CCURLY)) {
+        return NULL;
+    }
+
+    return node_block;
+}
+
+static ast_node_t *
+parser_parse_return_stmt(parser_t *parser)
+{
     if (!skip_expected_token(parser, TOKEN_RETURN)) {
         return NULL;
     }
@@ -338,17 +384,42 @@ parser_parse_block(parser_t *parser)
 
     node_return_stmt->as_return_stmt.data = expr;
 
-    list_append(node_block->as_block.nodes, node_return_stmt);
     if (!skip_expected_token(parser, TOKEN_LF)) {
         return NULL;
     }
-
     skip_line_feeds(parser->lexer);
-    if (!skip_expected_token(parser, TOKEN_CCURLY)) {
+
+    return node_return_stmt;
+}
+
+static ast_node_t *
+parser_parse_if_stmt(parser_t *parser)
+{
+    if (!skip_expected_token(parser, TOKEN_IF)) {
         return NULL;
     }
 
-    return node_block;
+    ast_node_t *cond = parser_parse_expr(parser);
+
+    if (cond == NULL) {
+        return NULL;
+    }
+
+    ast_node_t *then = parser_parse_block(parser);
+
+    if (then == NULL) {
+        return NULL;
+    }
+
+    ast_node_t *node_if_stmt = ast_new_node_if_stmt(parser->arena, cond, then);
+    assert(node_if_stmt);
+
+    if (!skip_expected_token(parser, TOKEN_LF)) {
+        return NULL;
+    }
+    skip_line_feeds(parser->lexer);
+
+    return node_if_stmt;
 }
 
 static bool
diff --git a/src/pretty_print_ast.c b/src/pretty_print_ast.c
index 6ca172f..c3debe3 100644
--- a/src/pretty_print_ast.c
+++ b/src/pretty_print_ast.c
@@ -161,6 +161,20 @@ ast_node_to_pretty_print_node(ast_node_t *ast, arena_t *arena)
 
             return node;
         }
+        case AST_NODE_IF_STMT: {
+            pretty_print_node_t *node = pretty_print_node_new(arena);
+            ast_if_stmt_t if_stmt = ast->as_if_stmt;
+
+            node->name = "If_Statement";
+
+            pretty_print_node_t *child = ast_node_to_pretty_print_node(if_stmt.cond, arena);
+            list_append(node->children, child);
+
+            child = ast_node_to_pretty_print_node(if_stmt.then, arena);
+            list_append(node->children, child);
+
+            return node;
+        }
         case AST_NODE_LITERAL: {
             pretty_print_node_t *node = pretty_print_node_new(arena);
             ast_literal_t literal = ast->as_literal;
diff --git a/tests/integration/tests/0020_if_statement.ol b/tests/integration/tests/0020_if_statement.ol
index f2f3262..ef3cd36 100644
--- a/tests/integration/tests/0020_if_statement.ol
+++ b/tests/integration/tests/0020_if_statement.ol
@@ -23,3 +23,18 @@ fn main(): u32 {
 # TEST test_contains_tokens WITH
 # ./tests/0020_if_statement.ol:17:3: <if>
 # END
+
+# TEST test_ast WITH
+# Translation_Unit
+# `-Function_Definition <name:main> <return:0>
+#   `-Block
+#     |-If_Statement
+#     | |-Binary_Operation (==)
+#     | | |-Literal <kind:u32> <value:1>
+#     | | `-Literal <kind:u32> <value:1>
+#     | `-Block
+#     |   `-Return_Statement
+#     |     `-Literal <kind:u32> <value:0>
+#     `-Return_Statement
+#       `-Literal <kind:u32> <value:1>
+# END
-- 
2.46.0