From 9a7d1b1d41f4b3bb3387e7bbe77105d0089803d0 Mon Sep 17 00:00:00 2001
From: ubq323 <ubq323@ubq323.website>
Date: Thu, 20 Jun 2024 18:43:01 +0100
Subject: globals are now variable

---
 com.c | 56 +++++++++++++++++++++++++++++++++++++-------------------
 dis.c |  9 +++++++++
 todo  |  4 ----
 vm.c  | 19 ++++++++++++++++++-
 vm.h  |  3 +++
 5 files changed, 67 insertions(+), 24 deletions(-)

diff --git a/com.c b/com.c
index ba45975..4252ecd 100644
--- a/com.c
+++ b/com.c
@@ -35,26 +35,44 @@ static void compile_node(State *S, Chunk *ch, AstNode a) {
 			CK(l.len == 2, "print requires exactly 1 argument");
 			compile_node(S, ch, l.vals[1]);
 			chunk_wbc(S, ch, OP_PRINT);
-			break;
-		}
-		CK(l.len == 3, "can only compile binary ops");
-		char opchar = l.vals[0].as.str[0];
-		Op op;
-		switch (opchar) {
-		#define OP(char, code) case char: op = code; break;
-			OP('+', OP_ADD)
-			OP('-', OP_SUB)
-			OP('*', OP_MUL)
-			OP('/', OP_DIV)
-		#undef OP
-			default:
-				printf("unkown op %s\n",l.vals[0].as.str);
-				exit(1);
-				break;
+		} else if (0 == strcmp(l.vals[0].as.str, "set")) {
+			CK(l.len == 3, "set requires exactly 2 arguments");
+			AstNode ident = l.vals[1];
+			CK(ident.ty == AST_IDENT, "set's first argument must be identifier");
+
+			size_t len = strlen(ident.as.str);
+			ObjString *o = objstring_copy(S, ident.as.str, len);
+
+			compile_node(S, ch, l.vals[2]);
+			chunk_wbc(S, ch, OP_SETGLOBAL);
+			chunk_wbc(S, ch, chunk_wconst(S, ch, VAL_OBJ(o)));
+		} else if (0 == strcmp(l.vals[0].as.str, "do")) {
+			for (int i = 1; i < l.len - 1; i++) {
+				compile_node(S, ch, l.vals[i]);
+				chunk_wbc(S, ch, OP_DROP);
+			}
+			compile_node(S, ch, l.vals[l.len - 1]);
+		} else {
+				
+			CK(l.len == 3, "can only compile binary ops");
+			char opchar = l.vals[0].as.str[0];
+			Op op;
+			switch (opchar) {
+			#define OP(char, code) case char: op = code; break;
+				OP('+', OP_ADD)
+				OP('-', OP_SUB)
+				OP('*', OP_MUL)
+				OP('/', OP_DIV)
+			#undef OP
+				default:
+					printf("unkown op %s\n",l.vals[0].as.str);
+					exit(1);
+					break;
+			}
+			compile_node(S, ch, l.vals[1]);
+			compile_node(S, ch, l.vals[2]);
+			chunk_wbc(S, ch, op);
 		}
-		compile_node(S, ch, l.vals[1]);
-		compile_node(S, ch, l.vals[2]);
-		chunk_wbc(S, ch, op);
 		#undef CK
 	}
 	}
diff --git a/dis.c b/dis.c
index 16c5b0e..0fb23f8 100644
--- a/dis.c
+++ b/dis.c
@@ -30,7 +30,16 @@ void disasm_chunk(Chunk *ch) {
 			println_val(k);
 			break;
 		}
+		case OP_SETGLOBAL: {
+			uint8_t ix = ch->bc.d[ip++];
+			printf("setglobal #%d\t; ",ix);
+			Val k = ch->consts.d[ix];
+			printf("%-4s : ",typename_str(k));
+			println_val(k);
+			break;
+		}
 		SIMPLE_INSTR(OP_PRINT, "print")
+		SIMPLE_INSTR(OP_DROP, "drop")
 		SIMPLE_INSTR(OP_ADD, "add")
 		SIMPLE_INSTR(OP_SUB, "sub")
 		SIMPLE_INSTR(OP_MUL, "mul")
diff --git a/todo b/todo
index 0dbc87d..2e920ed 100644
--- a/todo
+++ b/todo
@@ -1,7 +1,3 @@
-string interning
-	pass state through all allocation things
-	decide on state vs global state, terminology
-globals, getting and setting
 functions, returning
 locals, lexical scoping, closures, upvalues
 lists, hashes, other useful types
diff --git a/vm.c b/vm.c
index 00ba397..9f6ece6 100644
--- a/vm.c
+++ b/vm.c
@@ -56,6 +56,7 @@ void runvm(State *S) {
 
 #define PUSH(v) th->stack[th->sp++] = v;
 #define POP()   (th->stack[--th->sp])
+#define PEEK()  (th->stack[th->sp-1])
 
 	puts("---");
 	while (1) {
@@ -75,7 +76,10 @@ void runvm(State *S) {
 			break;
 		}
 		case OP_PRINT:
-			println_val(POP());
+			println_val(PEEK());
+			break;
+		case OP_DROP:
+			--th->sp;
 			break;
 
 		case OP_GETGLOBAL: {
@@ -90,6 +94,19 @@ void runvm(State *S) {
 			PUSH(v);
 			break;
 		}
+		case OP_SETGLOBAL: {
+			uint8_t cix = RBYTE();
+			Val varname = ch->consts.d[cix];
+			if (!IS_STRING(varname)) {
+				printf("global names must be string, not %s\n",
+					typename_str(varname));
+				goto done;
+			}
+			Val v = PEEK();
+
+			ht_put(S, &S->globals, AS_STRING(varname), v);
+			break;
+		}
 
 #define ARITH_OP(opcode, OP) \
 		case opcode: { \
diff --git a/vm.h b/vm.h
index bce1923..859e207 100644
--- a/vm.h
+++ b/vm.h
@@ -45,7 +45,10 @@ typedef enum {
 	OP_MUL,
 	OP_DIV,
 
+	OP_DROP,
+
 	OP_GETGLOBAL,
+	OP_SETGLOBAL,
 } Op;
 
 void runvm(State *S);
-- 
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