From 496ec36c8002a85dc0c3bb62de6d176e369b40af Mon Sep 17 00:00:00 2001
From: Bad Diode <bd@badd10de.dev>
Date: Sun, 3 Apr 2022 17:16:26 -0300
Subject: Add parsing for (set ...) statements

---
 src/lexer.c  |  2 +-
 src/nodes.c  |  7 +++++++
 src/nodes.h  |  6 ++++++
 src/parser.c | 33 +++++++++++++++++++++++++++++++++
 4 files changed, 47 insertions(+), 1 deletion(-)

(limited to 'src')

diff --git a/src/lexer.c b/src/lexer.c
index 2ccd577..729ea14 100644
--- a/src/lexer.c
+++ b/src/lexer.c
@@ -50,7 +50,7 @@ static const Keyword keywords[] = {
     KEYWORD("lambda", TOKEN_LAMBDA),
     KEYWORD("if",     TOKEN_IF),
     KEYWORD("def",    TOKEN_DEF),
-    KEYWORD("set!",   TOKEN_SET),
+    KEYWORD("set",    TOKEN_SET),
     KEYWORD("fun",    TOKEN_FUN),
     KEYWORD("struct", TOKEN_STRUCT),
     KEYWORD("+",      TOKEN_ADD),
diff --git a/src/nodes.c b/src/nodes.c
index 63e9b1f..855d186 100644
--- a/src/nodes.c
+++ b/src/nodes.c
@@ -56,6 +56,13 @@ print_node(Node *node) {
             print_node(node->def.value);
             printf(")");
         } break;
+        case NODE_SET: {
+            printf("(set ");
+            print_node(node->def.symbol);
+            printf(" ");
+            print_node(node->def.value);
+            printf(")");
+        } break;
         default: { printf("{#unknown#}"); } break;
     }
 }
diff --git a/src/nodes.h b/src/nodes.h
index e6ceb50..566d6d3 100644
--- a/src/nodes.h
+++ b/src/nodes.h
@@ -8,6 +8,7 @@ typedef enum NodeType {
     NODE_STRING,
     NODE_SYMBOL,
     NODE_DEF,
+    NODE_SET,
 } NodeType;
 
 typedef struct Node {
@@ -39,6 +40,11 @@ typedef struct Node {
             struct Node *value;
             StringView type;
         } def;
+
+        struct {
+            struct Node *symbol;
+            struct Node *value;
+        } set;
     };
 } Node;
 
diff --git a/src/parser.c b/src/parser.c
index cc94fd2..b36ddc9 100644
--- a/src/parser.c
+++ b/src/parser.c
@@ -177,6 +177,33 @@ parse_def(Parser *parser) {
     return node;
 }
 
+Node *
+parse_set(Parser *parser) {
+    Token op = next_token(parser);
+    Node *symbol = parse_next(parser);
+    if (symbol == NULL || symbol->type != NODE_SYMBOL) {
+        push_error(ERR_TYPE_PARSER, ERR_MALFORMED_EXPR, op.line, op.col);
+        return NULL;
+    }
+
+    Node *value = parse_next(parser);
+    if (value == NULL) {
+        push_error(ERR_TYPE_PARSER, ERR_MALFORMED_EXPR, op.line, op.col);
+        return NULL;
+    }
+
+    Token end = next_token(parser);
+    if (end.type != TOKEN_RPAREN) {
+        push_error(ERR_TYPE_PARSER, ERR_MALFORMED_EXPR, op.line, op.col);
+        return NULL;
+    }
+
+    Node *node = alloc_node(NODE_SET);
+    node->set.symbol = symbol;
+    node->set.value = value;
+    return node;
+}
+
 Node *
 parse_paren(Parser *parser) {
     next_token(parser); // Skip paren.
@@ -194,6 +221,7 @@ parse_paren(Parser *parser) {
         case TOKEN_OR: { return parse_builtin(parser); } break;
         // Special functions.
         case TOKEN_DEF: { return parse_def(parser); } break;
+        case TOKEN_SET: { return parse_set(parser); } break;
         default: break;
     }
 
@@ -202,6 +230,11 @@ parse_paren(Parser *parser) {
     return NULL;
 }
 
+
+// TODO: Parse if: (def ...) shouldn't be allowed for now on if statements. In
+// the future, an if can create a new block and thus a fresh scope which would
+// make the decision of what variables are active trivial.
+
 Node *
 parse_next(Parser *parser) {
     Token tok = peek_token(parser);
-- 
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