From 275b56622deb305a97165f5d84da0ed9df49a7d2 Mon Sep 17 00:00:00 2001
From: Puck Meerburg <puck@puckipedia.com>
Date: Sun, 11 May 2025 22:21:07 +0000
Subject: [PATCH] (zilch lang ninja): Support overriding source used for build

Change-Id: I6a6a696488f85192dbd911df3d2d28fee01f7b5b
---
 lang/ninja/src/config.sld  | 14 ++++++++++----
 lang/ninja/src/nixpkgs.sld | 14 +++++++++++++-
 2 files changed, 23 insertions(+), 5 deletions(-)

diff --git a/lang/ninja/src/config.sld b/lang/ninja/src/config.sld
index 378cea0..811dc69 100644
--- a/lang/ninja/src/config.sld
+++ b/lang/ninja/src/config.sld
@@ -2,12 +2,14 @@
  (import
   (scheme base) (scheme eval)
   (zilch magic) (zilch nixpkgs) (zilch vfs)
+  (srfi 88)
   (prefix (only scheme eval) scheme-))
 
  (export
   ninja-build-config?
   ninja-build-config-environment ninja-build-config-environment-drv
   ninja-build-config-root-dir ninja-build-config-patches ninja-build-config-targets
+  ninja-build-config-override-source
 
   set-ninja-build-config-root-dir! set-ninja-build-config-environment!
 
@@ -15,13 +17,14 @@
 
  (begin
    (define-record-type <ninja-build-config>
-    (make-ninja-build-config environment environment-drv root-dir patches targets)
+    (make-ninja-build-config environment environment-drv root-dir patches targets override-source)
     ninja-build-config?
     (environment ninja-build-config-environment set-ninja-build-config-environment!)
     (environment-drv ninja-build-config-environment-drv set-ninja-build-config-environment-drv!)
     (root-dir ninja-build-config-root-dir set-ninja-build-config-root-dir!)
     (patches ninja-build-config-patches set-ninja-build-config-patches!)
-    (targets ninja-build-config-targets set-ninja-build-config-targets!))
+    (targets ninja-build-config-targets set-ninja-build-config-targets!)
+    (override-source ninja-build-config-override-source set-ninja-build-config-override-source!))
 
    (define (parse-config-inner conf data)
     (cond
@@ -39,6 +42,9 @@
        ((#:root)
         (set-ninja-build-config-root-dir! conf (if (string? (list-ref data 1)) (vfs-from-directory (list-ref data 1)) (list-ref data 1)))
         (parse-config-inner conf (cddr data)))
+       ((#:override-source)
+        (set-ninja-build-config-override-source! conf (if (string? (list-ref data 1)) (vfs-from-directory (list-ref data 1)) (list-ref data 1)))
+        (parse-config-inner conf (cddr data)))
        ((#:patch)
         (let*
          ((patch-base (list-ref data 1))
@@ -59,9 +65,9 @@
           (list-val (if (list? val) val (list val))))
          (set-ninja-build-config-targets! conf (append list-val (ninja-build-config-targets conf))))
         (parse-config-inner conf (cddr data)))
-       (else (error (string-append "Unknown directive " (symbol->string (car data)) " parsing Zilch Ninja config")))))))
+       (else (error (string-append "Unknown directive " (keyword->string (car data)) " parsing Zilch Ninja config")))))))
 
    (define (parse-ninja-config config)
     (unless (list? config)
      (error "expected Zilch Ninja config to be a list"))
-    (parse-config-inner (make-ninja-build-config #f #f #f '() #f) config))))
+    (parse-config-inner (make-ninja-build-config #f #f #f '() #f #f) config))))
diff --git a/lang/ninja/src/nixpkgs.sld b/lang/ninja/src/nixpkgs.sld
index bd3e97b..425c51b 100644
--- a/lang/ninja/src/nixpkgs.sld
+++ b/lang/ninja/src/nixpkgs.sld
@@ -6,7 +6,7 @@
    (zilch magic) (zilch nixpkgs) (zilch vfs)
    (zilch nix drv)
    (zilch zexpr)
-   (srfi 132) (srfi 152))
+   (srfi 132) (srfi 146) (srfi 152))
 
  (export
   setup-ninja-environment
@@ -98,6 +98,18 @@
 
     ; This VFS contains two directories: `src` (source tree) and `build` (Ninja build files).
     (define configured-vfs (vfs-from-store configured-drv))
+    
+    (when (ninja-build-config-override-source conf)
+      (let
+        ((filtered (mapping-filter! (lambda (path val) (not (or (string=? "src" (car path)) (string-prefix? "src/" (car path))))) (vfs-contents configured-vfs))))
+        (mapping-for-each
+         (lambda (p v)
+          (set! filtered
+           (mapping-set! filtered
+            (cons (if (string=? (car p) "") "src" (string-append "src/" (car p))) (cdr p))
+            v)))
+         (vfs-contents (ninja-build-config-override-source conf)))
+        (set! configured-vfs (make-vfs filtered))))
 
     (set-ninja-build-config-root-dir! conf configured-vfs)