wip

aux.lua

@@ -0,0 +1,4 @@
+local Stack = require("stack_def")
+local aux = Stack.new(128)
+
+return aux

compiler.lua

@@ -17,7 +17,6 @@
 -- fix Lua's accidental global
 -- table
 --
-
 local stack = require("stack")
 local macros = require("macros")
 local ops = require("ops")
@@ -62,13 +61,13 @@ function compiler.emit_lua_call(self, name, arity, vararg)
   end
   local params = ""
   for i = 1, arity do
-    params = params .. "stack.pop()"
+    params = params .. "stack:pop()"
     if i < arity then
       params = params .. ", "
     end
   end
   -- TODO reverse the order of params?
-  self:emit_line("stack.push(" .. name .. "(" .. params .. "))")
+  self:emit_line("stack:push(" .. name .. "(" .. params .. "))")
 end
 
 function compiler.compile_token(self, token, kind)

dict.lua

@@ -33,6 +33,8 @@ dict.defword("not", "ops._not", false)
 dict.defword("and", "ops._and", false)
 dict.defword("or", "ops._or", false)
 dict.defword("..", "ops.concat", false)
+dict.defword(">a", "ops.to_aux", false)
+dict.defword("a>", "ops.from_aux", false)
 dict.defword("if", "macros._if", true)
 dict.defword("then", "macros._then", true)
 dict.defword("else", "macros._else", true)

macros.lua

@@ -33,35 +33,35 @@ end
 function macros.assignment(compiler)
   local alias = compiler:word()
   local name = "v_" .. alias
-  compiler:emit_line(name .. " = stack.pop()")
+  compiler:emit_line(name .. " = stack:pop()")
 end
 
 function macros._if(compiler)
   local label = gen_label()
-  compiler:emit_line("if not stack.pop() then goto " .. label .. " end")
-  stack.push(label)
+  compiler:emit_line("if not stack:pop() then goto " .. label .. " end")
+  stack:push(label)
 end
 
 function macros._else(compiler)
   local label = gen_label()
   compiler:emit_line("goto " .. label)
-  compiler:emit_line("::" .. stack.pop() .. "::")
-  stack.push(label)
+  compiler:emit_line("::" .. stack:pop() .. "::")
+  stack:push(label)
 end
 
 function macros._then(compiler)
-  compiler:emit_line("::" .. stack.pop() .. "::")
+  compiler:emit_line("::" .. stack:pop() .. "::")
 end
 
 function macros._begin(compiler)
   local label = gen_label()
   compiler:emit_line("::" .. label .. "::")
-  stack.push(label)
+  stack:push(label)
 end
 
 function macros._until(compiler)
-  local label = stack.pop()
-  compiler:emit_line("if not stack.pop() then goto " .. label .. " end")
+  local label = stack:pop()
+  compiler:emit_line("if not stack:pop() then goto " .. label .. " end")
 end
 
 function macros._end(compiler)

ops.lua

@@ -1,110 +1,119 @@
 local stack = require("stack")
+local aux = require("aux")
 local ops = {}
 
 function ops.dup()
-  stack.push(stack.tos())
+  stack:push(stack:tos())
 end
 
 function ops.add()
-  stack.push(stack.pop() + stack.pop())
+  stack:push(stack:pop() + stack:pop())
 end
 
 function ops.mul()
-  stack.push(stack.pop() * stack.pop())
+  stack:push(stack:pop() * stack:pop())
 end
 
 function ops.div()
-  local a = stack.pop()
-  local b = stack.pop()
-  stack.push(b / a)
+  local a = stack:pop()
+  local b = stack:pop()
+  stack:push(b / a)
 end
 
 function ops.sub()
-  local a = stack.pop()
-  local b = stack.pop()
-  stack.push(b - a)
+  local a = stack:pop()
+  local b = stack:pop()
+  stack:push(b - a)
 end
 
 function ops.depth()
-  stack.push(stack.depth())
+  stack:push(stack:depth())
 end
 
 function ops.swap()
-  local a = stack.pop()
-  local b = stack.pop()
-  stack.push(a)
-  stack.push(b)
+  local a = stack:pop()
+  local b = stack:pop()
+  stack:push(a)
+  stack:push(b)
 end
 
 function ops.over()
-  stack.push(stack.tos2())
+  stack:push(stack:tos2())
 end
 
 function ops.rot()
-  local c = stack.pop()
-  local b = stack.pop()
-  local a = stack.pop()
-  stack.push(b)
-  stack.push(c)
-  stack.push(a)
+  local c = stack:pop()
+  local b = stack:pop()
+  local a = stack:pop()
+  stack:push(b)
+  stack:push(c)
+  stack:push(a)
 end
 
 function ops.drop()
-  stack.pop()
+  stack:pop()
 end
 
 function ops.eq()
-  stack.push(stack.pop() == stack.pop())
+  stack:push(stack:pop() == stack:pop())
 end
 
 function ops.neq()
-  stack.push(stack.pop() ~= stack.pop())
+  stack:push(stack:pop() ~= stack:pop())
 end
 
 function ops.lt()
-  stack.push(stack.pop() > stack.pop())
+  stack:push(stack:pop() > stack:pop())
 end
 
 function ops.lte()
-  stack.push(stack.pop() >= stack.pop())
+  stack:push(stack:pop() >= stack:pop())
 end
 
 function ops.gt()
-  stack.push(stack.pop() < stack.pop())
+  stack:push(stack:pop() < stack:pop())
 end
 
 function ops.gte()
-  stack.push(stack.pop() <= stack.pop())
+  stack:push(stack:pop() <= stack:pop())
 end
 
 function ops._not()
-  stack.push(not stack.pop())
+  stack:push(not stack:pop())
 end
 
 function ops._and()
-  local a = stack.pop()
-  local b = stack.pop()
-  stack.push(a and b)
+  local a = stack:pop()
+  local b = stack:pop()
+  stack:push(a and b)
 end
 
 function ops._or()
-  local a = stack.pop()
-  local b = stack.pop()
-  stack.push(a or b)
+  local a = stack:pop()
+  local b = stack:pop()
+  stack:push(a or b)
 end
 
 function ops.concat()
-  local a = stack.pop()
-  local b = stack.pop()
-  stack.push(b .. a)
+  local a = stack:pop()
+  local b = stack:pop()
+  stack:push(b .. a)
 end
 
 function ops.dot()
-  print(stack.pop())
+  print(stack:pop())
 end
 
 function ops.lit(literal)
-  stack.push(literal)
+  stack:push(literal)
+end
+
+function ops.to_aux()
+  aux:push(stack:pop())
+end
+
+function ops.from_aux()
+  stack:push(aux:pop())
 end
 
 return ops

stack.lua

@@ -1,27 +1,4 @@
-local sp = 1
-local stack = {}
-for i = 1, 128 do stack[i] = nil end
-
-function stack.push(e)
-  stack[sp] = e
-  sp = sp + 1
-end
-
-function stack.pop()
-  sp = sp - 1
-  return stack[sp]
-end
-
-function stack.tos()
-  return stack[sp-1]
-end
-
-function stack.tos2()
-  return stack[sp-2]
-end
-
-function stack.depth()
-  return sp - 1
-end
+local Stack = require("stack_def")
+local stack = Stack.new(128)
 
 return stack

stack_def.lua

@@ -0,0 +1,32 @@
+local Stack = {}
+
+function Stack.new(size)
+  local obj = {stack = {}, sp = 1}
+  -- TODO check size, overflow / underflow
+  setmetatable(obj, {__index = Stack})
+  return obj
+end
+
+function Stack.push(self, e)
+  self.stack[self.sp] = e
+  self.sp = self.sp + 1
+end
+
+function Stack.pop(self)
+  self.sp = self.sp - 1
+  return self.stack[self.sp]
+end
+
+function Stack.tos(self)
+  return self.stack[self.sp-1]
+end
+
+function Stack.tos2(self)
+  return self.stack[self.sp-2]
+end
+
+function Stack.depth(self)
+  return self.sp - 1
+end
+
+return Stack

test_compiler.lua

@@ -5,12 +5,12 @@ compiler:eval_file("lib.eqx")
 
 function assert_tos(result, code)
   local stack = compiler:eval(code)
-  assert(stack.depth() == 1,
-         "'" .. code .. "' depth: " .. stack.depth())
-  assert(stack.tos() == result,
-         "'" .. code .. "' " .. tostring(stack.tos())
+  assert(stack:depth() == 1,
+         "'" .. code .. "' depth: " .. stack:depth())
+  assert(stack:tos() == result,
+         "'" .. code .. "' " .. tostring(stack:tos())
          .. " <> " .. tostring(result))
-  stack.pop()
+  stack:pop()
 end
 
 -- arithmetics - add
@@ -211,6 +211,10 @@ assert_tos(502, [[
   502 1002 math.min/2
 ]])
 
+assert_tos(0, [[
+ 1 2 >a 3 a> - -
+]])
+
 local status, result = pcall(
   function()
     return compiler:eval("1 2 math.min")