From 4b2cb6a1bdd2667ba827d17dde5fad955f2250bf Mon Sep 17 00:00:00 2001
From: Bad Diode <bd@badd10de.dev>
Date: Wed, 30 Mar 2022 17:07:12 +0200
Subject: Add initial parsing of variable definitions

---
 src/errors.c |  1 +
 src/errors.h |  1 +
 src/parser.c | 65 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++----
 src/parser.h | 10 +++++++++-
 4 files changed, 72 insertions(+), 5 deletions(-)

(limited to 'src')

diff --git a/src/errors.c b/src/errors.c
index 10b5ce1..e69e4f9 100644
--- a/src/errors.c
+++ b/src/errors.c
@@ -6,6 +6,7 @@ static const char* error_msgs[] = {
     [ERR_UNMATCHED_PAREN]  = "error: unbalanced parentheses",
     [ERR_UNKNOWN_TOK_TYPE] = "error: unknown token type",
     [ERR_MALFORMED_NUMBER] = "error: malformed number token",
+    [ERR_MALFORMED_EXPR]   = "error: malformed expression",
     [ERR_UNIMPLEMENTED]    = "error: not implemented",
 };
 
diff --git a/src/errors.h b/src/errors.h
index 155bb98..25f9945 100644
--- a/src/errors.h
+++ b/src/errors.h
@@ -14,6 +14,7 @@ typedef enum ErrorValue {
     ERR_UNKNOWN_TOK_TYPE,
     ERR_UNMATCHED_PAREN,
     ERR_MALFORMED_NUMBER,
+    ERR_MALFORMED_EXPR,
     ERR_UNIMPLEMENTED,
     ERR_OK,
 } ErrorValue;
diff --git a/src/parser.c b/src/parser.c
index 9703061..0b62ce4 100644
--- a/src/parser.c
+++ b/src/parser.c
@@ -107,6 +107,14 @@ parse_string(Parser *parser) {
     return node;
 }
 
+Node *
+parse_symbol(Parser *parser) {
+    Token tok = next_token(parser);
+    Node *node = alloc_node(NODE_SYMBOL);
+    node->string = tok.value;
+    return node;
+}
+
 Node *
 parse_bool(Parser *parser) {
     Token tok = next_token(parser);
@@ -137,12 +145,45 @@ parse_builtin(Parser *parser) {
     return NULL;
 }
 
+Node *
+parse_def(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;
+    }
+
+    // TODO: Check if it has type annotation.
+
+    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_DEF);
+    node->def.symbol = symbol;
+    node->def.value = value;
+
+    // TODO: Register variable in symbol table.
+
+    return node;
+}
+
 Node *
 parse_paren(Parser *parser) {
     next_token(parser); // Skip paren.
     Token tok = peek_token(parser);
-    // TODO: is keyword?
+
     switch (tok.type) {
+        // Builtin functions.
         case TOKEN_ADD:
         case TOKEN_SUB:
         case TOKEN_MUL:
@@ -153,11 +194,16 @@ parse_paren(Parser *parser) {
         case TOKEN_OR: {
             return parse_builtin(parser);
         } break;
+        // Special functions.
+        case TOKEN_DEF: {
+            return parse_def(parser);
+        } break;
         default: break;
     }
-    // print_token(tok);
-    // TODO: is in symbol table and its value is a function?
-    return NULL; // TODO: Not implemented
+
+    // TODO: Lookup value on symbol table.
+    push_error(ERR_TYPE_PARSER, ERR_UNIMPLEMENTED, tok.line, tok.col);
+    return NULL;
 }
 
 Node *
@@ -170,6 +216,9 @@ parse_next(Parser *parser) {
         case TOKEN_STRING: {
             return parse_string(parser);
         } break;
+        case TOKEN_SYMBOL: {
+            return parse_symbol(parser);
+        } break;
         case TOKEN_TRUE:
         case TOKEN_FALSE: {
             return parse_bool(parser);
@@ -200,6 +249,7 @@ print_node(Node *node) {
                 printf("%zu", node->number.integral);
             }
         } break;
+        case NODE_SYMBOL:
         case NODE_STRING: {
             sv_write(&node->string);
         } break;
@@ -225,6 +275,13 @@ print_node(Node *node) {
             }
             printf(")");
         } break;
+        case NODE_DEF: {
+            printf("(def ");
+            print_node(node->def.symbol);
+            printf(" ");
+            print_node(node->def.value);
+            printf(")");
+        } break;
         default: { printf("{#unk}"); } break;
     }
 }
diff --git a/src/parser.h b/src/parser.h
index c275195..de712e1 100644
--- a/src/parser.h
+++ b/src/parser.h
@@ -9,11 +9,12 @@ typedef struct Parser {
 } Parser;
 
 typedef enum NodeType {
-    // NODE_FUNCALL,
     NODE_BUILTIN,
     NODE_NUMBER,
     NODE_BOOL,
     NODE_STRING,
+    NODE_SYMBOL,
+    NODE_DEF,
 } NodeType;
 
 typedef struct Node {
@@ -38,6 +39,13 @@ typedef struct Node {
             TokenType type;
             struct Node **args;
         } builtin;
+
+        // Variable definition.
+        struct {
+            struct Node *symbol;
+            struct Node *value;
+            // TODO: type information
+        } def;
     };
 } Node;
 
-- 
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