place a trap inside the hex-transformed nlabel-transform-one

this will be used to cause it to apply a tilde alternate, but the lexing code for that needs to be refactored first

also, this has an implementation of nexit, a new flow-control word for a scary style of metaprogramming

Force-Push: yes
Change-Id: Ic7fe2d50a8ee21cf9fa5fef1fef4408c2935bb4c

1 files changed, 49 insertions, 0 deletions

diff --git a/transform.e b/transform.e
index 1d6d830..6d5907c 100644
--- a/transform.e
+++ b/transform.e
@@ -5279,6 +5279,54 @@ allocate-transformation-state s" transformation-state" variable
     } while drop ;
 
 
+: hex-label-word-replacement
+  word
+
+  value@
+  dup s" ~" stringcmp 0 = {
+    ~ We won't be going back to label-transform-one; clear away its state.
+    drop dropstring
+
+    ~   TODO we would very much like to run hex-tilde-alternate here, but it
+    ~ needs to be refactored first.
+    transformation-state transformation-state-saved-latest @
+    s" ~" find-in
+    entry-to-execution-token execute
+
+    ~   Return directly to label-transform, faking the "not done" return value
+    ~ from label-transform-one.
+    0
+    2 nexit
+  } if
+  drop ;
+
+
+~   Just as hex-allocate-alternate has the job of installing
+~ hex-allocate-replacement in only one single spot, so hex-word-alternate has
+~ the job of installing hex-label-word-replacement. It gets installed when
+~ "word" is called from lexically within label-transform-one, and at no other
+~ time.
+~
+~   Its structure is highly similar to that of hex-allocate-alternate.
+: hex-word-alternate
+  interpreter-flags @ 0x01 & {
+    ~ Compile mode.
+    latest @ entry-to-name dup s" label-transform-one" stringcmp 0 = {
+      ~ In label-transform-one.
+      drop
+      ' hex-label-word-replacement entry-to-execution-token ,
+    } {
+      ~ Not in label-transform-one.
+      drop
+      s" word" find entry-to-execution-token ,
+    } if-else
+  } {
+    ~ Immediate mode.
+    s" word" find
+    dup { entry-to-execution-token execute } { drop allocate } if-else
+  } if-else ; make-immediate
+
+
 ~   This implements the hex transform for a single word. It is directly
 ~ analogous to "interpret", and reading interpret.e may help in understanding
 ~ it, though it's meant to still make sense on its own.
@@ -5352,6 +5400,7 @@ allocate-transformation-state s" transformation-state" variable
   dup s" bye" stringcmp 0 = { swap drop ' hex-bye-alternate swap } if
   dup s" allocate" stringcmp 0 = {
     swap drop ' hex-allocate-alternate swap } if
+  dup s" word" stringcmp 0 = { swap drop ' hex-word-alternate swap } if
   dup s" ~" stringcmp 0 = { swap drop ' hex-tilde-alternate swap } if
   ~ (name as stack string, 0 or alternate entry pointer, name pointer)