Correct alias handling in pattern matching

1 files changed, 72 insertions, 37 deletions

diff --git a/src/Term.vala b/src/Term.vala
index 5c27e7f..e0033d6 100644
--- a/src/Term.vala
+++ b/src/Term.vala
@@ -8,13 +8,23 @@ namespace Eva {
     
     public Gee.Map<string, Term>? match(Term o) {
       Gee.Map<string, Term> vars = new Gee.HashMap<string, Term>();
-      if(!do_match(o, vars))
+      Gee.Map<string, string> aliases = new Gee.HashMap<string, string>();
+      if(!do_match(o, vars, aliases)) {
         return null;
-      else
+      }
+      else {
+        foreach(string a in aliases.keys) {
+          string v = Var.alias(a, aliases);
+          
+          if(v in vars)
+            vars[a] = vars[v];
+        }
+        
         return vars;
+      }
     }
     
-    protected abstract bool do_match(Term o, Gee.Map<string, Term> vars);
+    protected abstract bool do_match(Term o, Gee.Map<string, Term> vars, Gee.Map<string, string> aliases);
     
     public abstract void encode(Erl.Buffer buffer);
     
@@ -122,9 +132,9 @@ namespace Eva {
       return value.to_string();
     }
     
-    protected bool do_match(Term o, Gee.Map<string, Term> vars) {
+    protected bool do_match(Term o, Gee.Map<string, Term> vars, Gee.Map<string, string> aliases) {
       if(o is Var) {
-        return o.do_match(this, vars);
+        return o.do_match(this, vars, aliases);
       }
       
       if(o is Int) {
@@ -154,9 +164,9 @@ namespace Eva {
       return value.to_string();
     }
     
-    protected bool do_match(Term o, Gee.Map<string, Term> vars) {
+    protected bool do_match(Term o, Gee.Map<string, Term> vars, Gee.Map<string, string> aliases) {
       if(o is Var) {
-        return o.do_match(this, vars);
+        return o.do_match(this, vars, aliases);
       }
       
       if(o is Int) {
@@ -187,9 +197,9 @@ namespace Eva {
       return value.to_string();
     }
     
-    protected bool do_match(Term o, Gee.Map<string, Term> vars) {
+    protected bool do_match(Term o, Gee.Map<string, Term> vars, Gee.Map<string, string> aliases) {
       if(o is Var) {
-        return o.do_match(this, vars);
+        return o.do_match(this, vars, aliases);
       }
       
       if(o is Double) {
@@ -238,9 +248,9 @@ namespace Eva {
       }
     }
     
-    protected bool do_match(Term o, Gee.Map<string, Term> vars) {
+    protected bool do_match(Term o, Gee.Map<string, Term> vars, Gee.Map<string, string> aliases) {
       if(o is Var) {
-        return o.do_match(this, vars);
+        return o.do_match(this, vars, aliases);
       }
       
       if(o is Atom) {
@@ -283,9 +293,9 @@ namespace Eva {
       return ret + "}";
     }
     
-    protected bool do_match(Term o, Gee.Map<string, Term> vars) {
+    protected bool do_match(Term o, Gee.Map<string, Term> vars, Gee.Map<string, string> aliases) {
       if(o is Var) {
-        return o.do_match(this, vars);
+        return o.do_match(this, vars, aliases);
       }
       
       if(!(o is Tuple))
@@ -297,7 +307,7 @@ namespace Eva {
         return false;
       
       for(int i = 0; i < value.size; ++i) {
-        if(!value[i].do_match(t.value[i], vars))
+        if(!value[i].do_match(t.value[i], vars, aliases))
           return false;
       }
       
@@ -340,9 +350,9 @@ namespace Eva {
       tail = null;
     }
     
-    protected bool do_match(Term o, Gee.Map<string, Term> vars) {
+    protected bool do_match(Term o, Gee.Map<string, Term> vars, Gee.Map<string, string> aliases) {
       if(o is Var) {
-        return o.do_match(this, vars);
+        return o.do_match(this, vars, aliases);
       }
       
       if(o is List) {
@@ -352,13 +362,13 @@ namespace Eva {
           return false;
         if((tail == null) != (l.tail == null))
           return false;
-        if(tail != null && !tail.do_match(l.tail, vars))
+        if(tail != null && !tail.do_match(l.tail, vars, aliases))
           return false;
         
         Gee.Iterator<Term> lt = l.list.iterator();
         lt.first();
         foreach(Term t in list) {
-          if(!t.do_match(lt.get(), vars))
+          if(!t.do_match(lt.get(), vars, aliases))
             return false;
           
           lt.next();
@@ -453,16 +463,16 @@ namespace Eva {
       return "\"" + value.replace("\\", "\\\\").replace("\"", "\\\"") + "\"";
     }
     
-    protected bool do_match(Term o, Gee.Map<string, Term> vars) {
+    protected bool do_match(Term o, Gee.Map<string, Term> vars, Gee.Map<string, string> aliases) {
       if(o is Var) {
-        return o.do_match(this, vars);
+        return o.do_match(this, vars, aliases);
       }
       
       if(o is String) {
         return (value == (o as String).value);
       }
       else if(o is List) {
-        return o.do_match(this, vars);
+        return o.do_match(this, vars, aliases);
       }
       else {
         return false;
@@ -493,9 +503,9 @@ namespace Eva {
       return "#Bin";
     }
     
-    protected bool do_match(Term o, Gee.Map<string, Term> vars) {
+    protected bool do_match(Term o, Gee.Map<string, Term> vars, Gee.Map<string, string> aliases) {
       if(o is Var) {
-        return o.do_match(this, vars);
+        return o.do_match(this, vars, aliases);
       }
       
       if(o is Binary) {
@@ -535,9 +545,9 @@ namespace Eva {
       return "<" + node + "." + num.to_string() + "." + serial.to_string() + ">";
     }
     
-    protected bool do_match(Term o, Gee.Map<string, Term> vars) {
+    protected bool do_match(Term o, Gee.Map<string, Term> vars, Gee.Map<string, string> aliases) {
       if(o is Var) {
-        return o.do_match(this, vars);
+        return o.do_match(this, vars, aliases);
       }
       
       if(!(o is Pid))
@@ -581,9 +591,9 @@ namespace Eva {
       return "#Port";
     }
     
-    protected bool do_match(Term o, Gee.Map<string, Term> vars) {
+    protected bool do_match(Term o, Gee.Map<string, Term> vars, Gee.Map<string, string> aliases) {
       if(o is Var) {
-        return o.do_match(this, vars);
+        return o.do_match(this, vars, aliases);
       }
       
       if(!(o is Port))
@@ -632,9 +642,9 @@ namespace Eva {
       return "#Ref";
     }
     
-    protected bool do_match(Term o, Gee.Map<string, Term> vars) {
+    protected bool do_match(Term o, Gee.Map<string, Term> vars, Gee.Map<string, string> aliases) {
       if(o is Var) {
-        return o.do_match(this, vars);
+        return o.do_match(this, vars, aliases);
       }
       
       if(!(o is Ref))
@@ -687,17 +697,42 @@ namespace Eva {
       return name;
     }
     
-    protected bool do_match(Term o, Gee.Map<string, Term> vars) {
-      if(o is Var) {
-        return name == (o as Var).name;
-      }
+    internal static string alias(string key, Gee.Map<string, string> aliases) {
+      if(!(key in aliases))
+        return key;
+      else
+        return alias(aliases[key], aliases);
+    }
+    
+    protected bool do_match(Term o, Gee.Map<string, Term> vars, Gee.Map<string, string> aliases) {
+      string key = alias(name, aliases);
       
-      if(name in vars) {
-        return vars[name].do_match(o, vars);
+      if(o is Var) {
+        Var v = o as Var;
+        string vkey = alias(v.name, aliases);
+        
+        if(key == vkey)
+          return true;
+        
+        if(key in vars && vkey in vars)
+          return vars[key].do_match(vars[vkey], vars, aliases);
+        else if(!(vkey in vars)) {
+          aliases[vkey] = key;
+          return true;
+        }
+        else /* !(key in vars) */ {
+          aliases[key] = vkey;
+          return true;
+        }
       }
       else {
-        vars[name] = o;
-        return true;
+        if(key in vars) {
+          return vars[key].do_match(o, vars, aliases);
+        }
+        else {
+          vars[key] = o;
+          return true;
+        }
       }
     }