Add expression variables, solution for #2

README.md

@@ -77,20 +77,37 @@ Temporary variables for use in the code can be defined with the following syntax
 
     <type> <name> = <expression>
 
+Variables used in expressions must have already been defined earlier in the code before they can be used. Duplicate variable names are not allowed. Variables cannot be reassigned after creation (with the exception of the loop variable generated by for loops, which are automatically reassigned throughout the loop). 
+
 The supported types are: 
 
 - int 
 - signal 
 - condition 
 - circuit 
+- expression
 
 `int` types are numeric expressions, and `signal` types are signals.
 
 `condition` types are numeric expressions that can directly map to a decider combinator's config. This essentially means that it must be an expression of the form `<signal> <c_op> <expression>`, where `c_op` is either `==`, `!=`, `>`, `>=`, `<`, or `<=`, and `expression` is a numeric expression without any signals. 
 
 `circuit` types are circuits, which can be the name of a circuit that was previously bound, a pattern call, or a `for` expression. 
 
-Variables used in expressions must have already been defined earlier in the code before they can be used. Duplicate variable names are not allowed. 
+
+`expression` types are simply any expression that serve as a sort of copy-paste shorthand for reusing the same block of logic. For example, the following two code snippets are equivalent:
+
+```
+circuit c1 : D = (A + B - C) / 45;
+circuit c2 : E = (A + B - C) - (G * H);
+```
+
+with an `expression` variable:
+
+```
+expression expr = A + B + C;
+circuit c1 : D = expr / 45;
+circuit c2 : E = expr - (G * H);
+```
 
 ### Output 
 

combc.opam

@@ -1,6 +1,6 @@
 # This file is generated by dune, edit dune-project instead
 opam-version: "2.0"
-version: "0.2.10"
+version: "0.2.11"
 synopsis: "C-style language that compiles to Factorio combinators"
 maintainer: ["Owen Simon <osimon922@gmail.com>"]
 authors: ["Owen Simon <osimon922@gmail.com>"]

dune-project

@@ -1,7 +1,7 @@
 (lang dune 3.0)
 (using menhir 2.1)
 (name combc)
-(version 0.2.10)
+(version 0.2.11)
 (license "GPL-3.0")
 (authors "Owen Simon <osimon922@gmail.com>")
 (maintainers "Owen Simon <osimon922@gmail.com>")

src/ast/expression.ml

@@ -3,6 +3,7 @@ open Circuit
 
 type var_type = 
 | TInt
+| TStamp
 | TCondition
 | TSignal
 | TCircuit
@@ -11,6 +12,7 @@ type var_type =
 let string_of_type ty : string = 
   begin match ty with 
   | TInt -> "int"
+  | TStamp -> "expression"
   | TCondition -> "condition"
   | TSignal -> "signal"
   | TCircuit -> "circuit"
@@ -48,6 +50,7 @@ type compiled_circuit =
 type expression = 
 | Call of string * delayed_expression list 
 | Int of int32
+| Stamp of bexp
 | Condition of bexp  
 | Var of string 
 | Signal of string 

src/compiler/compile.ml

@@ -187,6 +187,7 @@ let json_of_bexp (o_sig:symbol) (b: bexp) : json list =
 let interpret_type exp : var_type * expression = 
     begin match exp with 
     | Int _ -> TInt 
+    | Stamp _ -> TStamp
     | Condition _ -> TCondition
     | Signal _ -> TSignal
     | Circuit _ 
@@ -207,16 +208,16 @@ let rec bottom_out_var e : expression =
   end 
 
 
-let expression_of_delayed exp = 
+let expression_of_delayed (exp: delayed_expression) : expression = 
   begin match exp with 
-          | Immediate exp -> exp 
-          | Delayed bexp -> 
-            let bexp = bind_vars_of_bexp bexp in
-            begin match expression_of_bexp bexp with 
-            | Immediate exp -> exp 
-            | Delayed _ -> Circuit (Inline (bexp, "check", None))
-            end  
-        end
+    | Immediate exp -> exp 
+    | Delayed bexp -> 
+      let bexp = bind_vars_of_bexp bexp in
+      begin match expression_of_bexp bexp with 
+      | Immediate exp -> exp 
+      | Delayed _ -> Circuit (Inline (bexp, "check", None))
+      end  
+  end
 
 let rec evaluate_expression (expression:expression) : expression = 
   let rec inter exp = 
@@ -253,6 +254,7 @@ let rec evaluate_expression (expression:expression) : expression =
           Circuit (Compiled c) 
       | Signal _ 
       | Int _ 
+      | Stamp _ 
       | Circuit _
       | Pattern _ -> exp
       end in 
@@ -291,6 +293,7 @@ and compile_ctree_to_circuit (ctree:ctree) : compiled_circuit =
       begin match e with 
       | Signal _ 
       | Condition _
+      | Stamp _
       | Int _ -> Abstract (compile_bexp_to_circuit o_sig ast)
       | Circuit c -> compile_ctree_to_circuit c 
       | _ -> prerr_endline "Cannot bind variable to circuit. This error should never occur"; exit 1
@@ -377,7 +380,8 @@ and evaluate_expression_to_ctree exp loc : compiled_circuit =
       begin match exp with 
       | Signal s -> Inline (Signal s, s, loc)
       | Int i -> Inline (Lit i, "signal-check", loc)
-      | Condition b -> Inline (b, "signal-check", loc)
+      | Condition b 
+      | Stamp b -> Inline (b, "signal-check", loc)
       | Circuit c -> c
       | Pattern _ -> prerr_endline "Can't evaluate pattern to circuit. Did you mean to provide arguments?"; exit 1
       | _ -> failwith "Expression not reduced! Impossible error"

src/compiler/firstPhase.ml

@@ -109,9 +109,10 @@ let bind_vars_of_bexp bexp : bexp =
   | Var var -> 
     let ty, v = Ctxt.lookup var in 
     begin match v with 
-    | Int i -> Lit i 
+    | Int x -> Lit x 
     | Signal s -> Signal s 
-    | Condition b -> i b
+    | Condition b 
+    | Stamp b -> i b 
     | Var v -> i (Var v)
     | _ -> prerr_endline (Printf.sprintf "Can't bind variable \"%s\" of type \"%s\" to expression" var (Ast.Expression.string_of_type ty)) ; exit 1 
     end    

src/parser/lexer.mll

@@ -28,6 +28,7 @@
   ("int", TINT);
   ("signal", TSIGNAL);  
   ("condition", TCONDITION);
+  ("expression", TSTAMP);
 
   ("{", LBRACE);
   ("}", RBRACE);

src/parser/parser.mly

@@ -89,6 +89,7 @@ open Compiler.Directive;;
 %token TINT 
 %token TSIGNAL 
 %token TCONDITION
+%token TSTAMP
 
 %start toplevel
 
@@ -126,6 +127,7 @@ command:
 
   | TINT i=IDENT ASSIGN b=bexp SEMI                                   { Assign(i, TInt, expression_of_bexp b)  }
   | TCONDITION i=IDENT ASSIGN b=bexp SEMI                             { Assign(i, TCondition, expression_of_bexp b)  }
+  | TSTAMP i=IDENT ASSIGN b=bexp SEMI                                 { Assign(i, TStamp, Immediate (Stamp b))  }
   | TSIGNAL i=IDENT ASSIGN b=bexp SEMI                                { Assign(i, TSignal, expression_of_bexp b)  }
   | o=output SEMI                                                     { o }