refactor label resolution into its own method

lips/Preproc.lua

@@ -36,7 +36,10 @@ function Preproc:lookup(t)
         if t.tok == nil then
             self:error('undefined variable', name)
         end
-    elseif self.do_labels and t.tt == 'RELLABELSYM' or t.tt == 'RELLABEL' then
+    end
+end
+
+function Preproc:resolve(t)
     if t.tt == 'RELLABEL' then
         t.tt = 'LABEL'
         -- exploits the fact that user labels can't begin with a number
@@ -82,10 +85,6 @@ function Preproc:lookup(t)
             self:error('could not find appropriate relative label', t.tok)
         end
     end
-    else
-        return false
-    end
-    return true
 end
 
 function Preproc:check(s, i, tt)
@@ -115,7 +114,6 @@ function Preproc:process(statements)
     self.variables = {}
     self.plus_labels = {} -- constructed forwards
     self.minus_labels = {} -- constructed backwards
-    self.do_labels = false
 
     -- first pass: resolve variables and collect relative labels
     local new_statements = {}
@@ -152,10 +150,9 @@ function Preproc:process(statements)
     end
 
     -- second pass: resolve relative labels
-    self.do_labels = true
     for s in self:iter(new_statements) do
         for j, t in ipairs(s) do
-            self:lookup(t)
+            self:resolve(t)
         end
     end