From 58dfde37752f87e5df850ebe3a324dcb825fdb35 Mon Sep 17 00:00:00 2001
From: Bad Diode <bd@badd10de.dev>
Date: Sat, 30 Oct 2021 09:02:55 +0200
Subject: Add parsing for fun expressions

---
 src/lexer.c  |  2 ++
 src/lexer.h  |  1 +
 src/parser.c | 43 +++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 46 insertions(+)

(limited to 'src')

diff --git a/src/lexer.c b/src/lexer.c
index 704ee66..09c8f6c 100755
--- a/src/lexer.c
+++ b/src/lexer.c
@@ -15,6 +15,7 @@ static const char* token_str[] = {
     [TOKEN_IF]      = "TOKEN_IF",
     [TOKEN_DEF]     = "TOKEN_DEF",
     [TOKEN_SET]     = "TOKEN_SET",
+    [TOKEN_FUN]     = "TOKEN_FUN",
     [TOKEN_EOF]     = "TOKEN_EOF",
 };
 
@@ -132,6 +133,7 @@ find_primitive_type(const StringView value) {
     if (TOKEN_IS_KEYWORD(value, "if")) { return TOKEN_IF; }
     if (TOKEN_IS_KEYWORD(value, "def")) { return TOKEN_DEF; }
     if (TOKEN_IS_KEYWORD(value, "set!")) { return TOKEN_SET; }
+    if (TOKEN_IS_KEYWORD(value, "fun")) { return TOKEN_FUN; }
 
     return TOKEN_SYMBOL;
 }
diff --git a/src/lexer.h b/src/lexer.h
index f187526..c477fbd 100755
--- a/src/lexer.h
+++ b/src/lexer.h
@@ -23,6 +23,7 @@ typedef enum TokenType {
     TOKEN_IF,
     TOKEN_DEF,
     TOKEN_SET,
+    TOKEN_FUN,
 
     // End of file.
     TOKEN_EOF,
diff --git a/src/parser.c b/src/parser.c
index f831e50..e32a571 100644
--- a/src/parser.c
+++ b/src/parser.c
@@ -116,6 +116,15 @@ parse_lambda(Parser *parser, Errors *errors) {
         Object *expr = parse_tree(parser, errors);
         array_push(lambda->body, expr);
     }
+    if (array_size(lambda->body) == 0) {
+        error_push(errors, (Error){
+            .type = ERR_TYPE_PARSER,
+            .value = ERR_NOT_ENOUGH_ARGS,
+            .line = start.line,
+            .col = start.col,
+        });
+        return NULL;
+    }
     return lambda;
 }
 
@@ -226,6 +235,39 @@ parse_var(Parser *parser, Errors *errors) {
     return ret;
 }
 
+Object *
+parse_fun(Parser *parser, Errors *errors) {
+    Token start = next_token(parser);
+    Object *ret = object_alloc(start, OBJ_TYPE_DEF);
+
+    // Variable name.
+    Token tok = peek_token(parser);
+    if (tok.type == TOKEN_RPAREN) {
+        error_push(errors, (Error){
+            .type = ERR_TYPE_PARSER,
+            .value = ERR_NOT_ENOUGH_ARGS,
+            .line = tok.line,
+            .col = tok.col,
+        });
+        return NULL;
+    }
+    if (tok.type != TOKEN_SYMBOL) {
+        error_push(errors, (Error){
+            .type = ERR_TYPE_PARSER,
+            .value = ERR_WRONG_ARG_TYPE,
+            .line = tok.line,
+            .col = tok.col,
+        });
+        return NULL;
+    }
+    ret->var_name = parse_tree(parser, errors);
+
+    // Variable value (expression).
+    rewind_token(parser);
+    ret->var_expr = parse_lambda(parser, errors);
+    return ret;
+}
+
 Object *
 parse_list(Parser *parser, Errors *errors) {
     if (errors->n != 0) {
@@ -247,6 +289,7 @@ parse_list(Parser *parser, Errors *errors) {
         case TOKEN_IF: { return parse_if(parser, errors); } break;
         case TOKEN_DEF: { return parse_var(parser, errors); } break;
         case TOKEN_SET: { return parse_var(parser, errors); } break;
+        case TOKEN_FUN: { return parse_fun(parser, errors); } break;
         default: break;
     }
 
-- 
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