From 16e29c9dc9fc12e4c4c68ed0b7da648608b3372b Mon Sep 17 00:00:00 2001
From: Cat's Eye Technologies <cpressey@catseye.tc>
Date: Tue, 1 Apr 2014 13:29:45 +0100
Subject: [PATCH] Checks for undeclared locations.

---
 README.markdown           | 30 +++++++++++++++++++++++++++---
 src/SixtyPical/Checker.hs | 34 +++++++++++++++++++++++++---------
 2 files changed, 52 insertions(+), 12 deletions(-)

diff --git a/README.markdown b/README.markdown
index 3a7c90f..918aa18 100644
--- a/README.markdown
+++ b/README.markdown
@@ -110,9 +110,9 @@ Tests
 A program may reserve and assign.
 
     | reserve word score
-    | assign word scram 4000
+    | assign word screen 4000
     | routine main {
-    |    lda scram
+    |    lda screen
     |    cmp score
     | }
     = True
@@ -120,7 +120,31 @@ A program may reserve and assign.
 All declarations (`reserve`s and `assign`s) must come before any `routines`.
 
     | routine main {
-    |    lda scram
+    |    lda score
     | }
     | reserve word score
     ? expecting "routine"
+
+All locations used in all routines must be declared first.
+
+    | reserve word score
+    | routine main {
+    |    lda score
+    |    cmp screen
+    | }
+    ? undeclared location
+
+Even in inner blocks.
+
+    | reserve word score
+    | assign word screen 4000
+    | routine main {
+    |    lda score
+    |    cmp screen
+    |    beq {
+    |      lda score
+    |    } else {
+    |      lda fnord
+    |    }
+    | }
+    ? undeclared location
diff --git a/src/SixtyPical/Checker.hs b/src/SixtyPical/Checker.hs
index 94d2883..26ac73f 100644
--- a/src/SixtyPical/Checker.hs
+++ b/src/SixtyPical/Checker.hs
@@ -4,6 +4,11 @@ module SixtyPical.Checker where
 
 import SixtyPical.Model
 
+allTrue = foldl (&&) True
+
+trueOrDie message test =
+    if test then True else error message
+
 routineDeclared routName (Program _ routines) =
     elem routName (map (getRoutineName) routines)
     where
@@ -15,16 +20,27 @@ locationDeclared locName (Program decls _) =
         getLocationName (Assign name _ _) = name
         getLocationName (Reserve name _) = name
 
-mainDeclared program =
-    if
-        routineDeclared "main" program
-      then
-        True
-      else
-        error "missing 'main' routine"
+routineUsedLocations (Routine _ instrs) = blockUsedLocations instrs
+
+blockUsedLocations [] = []
+blockUsedLocations (instr:instrs) =
+    (instrUsedLocations instr) ++ blockUsedLocations instrs
+
+instrUsedLocations (LOAD reg loc) = [loc]
+instrUsedLocations (CMP reg loc) = [loc]
+-- TODO: JSR...
+instrUsedLocations (IFEQ b1 b2) =
+    blockUsedLocations b1 ++ blockUsedLocations b2
+instrUsedLocations _ = []
+
+allRoutineLocationsDeclared program routine =
+    allTrue (map (isDeclared) (routineUsedLocations routine))
+    where
+        isDeclared name = locationDeclared name program
 
 allUsedLocationsDeclared p@(Program _ routines) =
-    True
+    allTrue (map (allRoutineLocationsDeclared p) routines)
 
 checkProgram program =
-    mainDeclared program && allUsedLocationsDeclared program
+    trueOrDie "missing 'main' routine" (routineDeclared "main" program) &&
+      trueOrDie "undeclared location" (allUsedLocationsDeclared program)