microscript: add globals

1 files changed, 47 insertions, 4 deletions

diff --git a/uscript/parser.c b/uscript/parser.c
index 404e5e5..89a8883 100644
--- a/uscript/parser.c
+++ b/uscript/parser.c
@@ -185,6 +185,21 @@ int find_local(struct func_parser *fp, struct token name)
 }
 
 static
+int find_global(struct token name)
+{
+        for (int i = da_len(vm.gstack) - 1; i >= 0; i--) {
+                struct global global = vm.gstack[i];
+                if (
+                        (size_t)name.len == global.name->len &&
+                        memcmp(name.start, global.name->chars, name.len) == 0
+                )
+                        return i;
+        }
+
+        return -1;
+}
+
+static
 int find_upval(struct parser *p, struct func_parser *fp, struct token name)
 {
         if (fp == NULL)
@@ -383,6 +398,9 @@ void parse_ident(struct parser *p)
         } else if ((var = find_upval(p, p->fp, ident)) != -1) {
                 setter = BC_SET_UPVAL;
                 getter = BC_GET_UPVAL;
+        } else if ((var = find_global(ident)) != -1) {
+                setter = BC_SET_GLOBAL;
+                getter = BC_GET_GLOBAL;
         }
 
         if (var == -1) {
@@ -396,7 +414,13 @@ void parse_ident(struct parser *p)
         } else {
                 parser_add_byte(p, getter);
         }
-        parser_add_byte(p, (u8)var);
+
+        if (setter == BC_SET_GLOBAL) {
+                parser_add_byte(p, (var >> 8) & 0xFF);
+                parser_add_byte(p, var & 0xFF);
+        } else {
+                parser_add_byte(p, (u8)var);
+        }
 }
 
 static
@@ -576,7 +600,7 @@ void expr_stat(struct parser *p)
 }
 
 static
-void let_stat(struct parser *p)
+void var_def_stat(struct parser *p, bool is_global)
 {
         do {
                 expect(p, TOKEN_IDENT, "expected variable name");
@@ -587,7 +611,16 @@ void let_stat(struct parser *p)
                 else
                         parser_add_byte(p, BC_ZILCH);
 
-                declare_variable(p, name);
+                if (is_global) {
+                        struct us_str *ident = copy_str(name.start, name.len);
+                        int idx = declare_global(ident);
+                        parser_add_byte(p, BC_SET_GLOBAL);
+                        parser_add_byte(p, (idx >> 8) & 0xFF);
+                        parser_add_byte(p, idx & 0xFF);
+                        parser_add_byte(p, BC_POP); // set global does not pop
+                } else {
+                        declare_variable(p, name);
+                }
         } while (consume(p, ','));
 }
 
@@ -824,7 +857,17 @@ static
 void stat(struct parser *p)
 {
         if (consume(p, TOKEN_LET)) {
-                let_stat(p);
+                var_def_stat(p, false);
+                consume(p, ';');
+        } else if (consume(p, TOKEN_GLOBAL)) {
+                if (!p->fp->is_script) {
+                        show_error(
+                                p,
+                                p->cur,
+                                "can only define globals in the outermost scope"
+                        );
+                }
+                var_def_stat(p, true);
                 consume(p, ';');
         } else if (consume(p, TOKEN_FUN)) {
                 fun_stat(p);