From b50d606bdd0fbda3451e9fcb07e8096fa5bee55b Mon Sep 17 00:00:00 2001
From: tomsmeding <hallo@tomsmeding.nl>
Date: Sun, 6 Sep 2015 22:18:30 +0200
Subject: Add scopes!

---
 bf.prn        |  2 +-
 functions.cpp | 30 ++++++++++++++++++++++++++++++
 runtime.cpp   |  2 ++
 3 files changed, 33 insertions(+), 1 deletion(-)

diff --git a/bf.prn b/bf.prn
index acaa6c1..19d1368 100644
--- a/bf.prn
+++ b/bf.prn
@@ -80,7 +80,7 @@ dup 0 > while
 		c ">" = if -1 roll end
 		c "<" = if 1 roll end
 		c "]" = if
-			i "loopend" depth 1 - + store
+			i "loopend" depth 1 - + gstore
 			len "i" store  # == break
 		end
 		c "[" = if
diff --git a/functions.cpp b/functions.cpp
index 4795c93..9655e5a 100644
--- a/functions.cpp
+++ b/functions.cpp
@@ -1,7 +1,9 @@
 #include <iostream>
 #include <fstream>
 #include <unordered_map>
+#include <unordered_set>
 #include <vector>
+#include <stack>
 #include <string>
 #include <functional>
 #include <unistd.h>
@@ -16,6 +18,8 @@ extern char **g_argv;
 
 #define BUILTIN_GUARD_STACKSIZE(nm,sz) {if(S.size()<(sz))throw string("Builtin '" nm "' needs " #sz " stack item")+(sz==1?"":"s");}
 
+stack<unordered_set<string>> scopestack;
+
 //please extern this shit with const!
 unordered_map<string,function<void(vector<Stackitem>&,unordered_map<string,Stackitem>&)>> builtins={
 	{"+",[](vector<Stackitem> &S,unordered_map<string,Stackitem> &variables){
@@ -207,6 +211,18 @@ unordered_map<string,function<void(vector<Stackitem>&,unordered_map<string,Stack
 		BUILTIN_GUARD_STACKSIZE("store",2)
 		Stackitem name=move(S.back()); S.pop_back();
 		if(!name.isstr)throw string("Second argument to 'store' not a string");
+		auto it=variables.find(name.strval);
+		bool exists=it!=variables.end();
+		//insert_or_assign is C++17 sadly
+		/*if(exists)variables.insert(it,make_pair(name.strval,move(S.back())));
+		else*/ variables[name.strval]=move(S.back());
+		S.pop_back();
+		if(scopestack.size()&&!exists)scopestack.top().insert(name.strval);
+	}},
+	{"gstore",[](vector<Stackitem> &S,unordered_map<string,Stackitem> &variables){
+		BUILTIN_GUARD_STACKSIZE("gstore",2)
+		Stackitem name=move(S.back()); S.pop_back();
+		if(!name.isstr)throw string("Second argument to 'store' not a string");
 		variables[name.strval]=move(S.back());
 		S.pop_back();
 	}},
@@ -224,6 +240,20 @@ unordered_map<string,function<void(vector<Stackitem>&,unordered_map<string,Stack
 		S.push_back(move(variables[name.strval]));
 		variables[name.strval].intval=0;
 	}},
+	{"enterscope",[](vector<Stackitem> &S,unordered_map<string,Stackitem> &variables){
+		//cerr<<"scope enter"<<endl;
+		scopestack.emplace();
+	}},
+	{"leavescope",[](vector<Stackitem> &S,unordered_map<string,Stackitem> &variables){
+		if(scopestack.size()<1)throw string("Scope stack empty while requesting scope leave");
+		//cerr<<"scope leave: ";
+		for(const string &varname : scopestack.top()){
+			variables.erase(varname);
+			//cerr<<varname<<' ';
+		}
+		//cerr<<endl;
+		scopestack.pop();
+	}},
 	//positive n: roll OFF top to bottom; negative n: roll off bottom ONTO top
 	{"roll",[](vector<Stackitem> &S,unordered_map<string,Stackitem> &variables){
 		BUILTIN_GUARD_STACKSIZE("roll",1)
diff --git a/runtime.cpp b/runtime.cpp
index 63e0b52..3cf607d 100644
--- a/runtime.cpp
+++ b/runtime.cpp
@@ -129,7 +129,9 @@ void runpasseval(const vector<string> &T,
 			} else {
 				auto it=functions.find(word);
 				if(it!=functions.end()){
+					builtins.find("enterscope")->second(S,variables);
 					runpasseval(it->second.first,S,functions,variables,it->second.second);
+					builtins.find("leavescope")->second(S,variables);
 				} else {
 					if(word=="while"){
 						if(S.size()<1)throw string("Keyword 'while' needs 1 stack item");
-- 
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