Pipeline backend is done and works.

backends.py

@@ -85,6 +85,7 @@ class Backend():
             return
         self.process_target_dependencies(target, outfile)
         print('Generating target', name)
+        self.generate_custom_generator_rules(target, outfile)
         outname = self.get_target_filename(target)
         obj_list = []
         if target.has_pch():
@@ -347,6 +348,29 @@ class NinjaBackend(Backend):
             outfile.write('\n')
         outfile.write('\n')
 
+    def generate_custom_generator_rules(self, target, outfile):
+        for genlist in target.get_generated_sources():
+            generator = genlist.get_generator()
+            exe = generator.get_exe()
+            infilelist = genlist.get_infilelist()
+            outfilelist = genlist.get_outfilelist()
+            if len(infilelist) != len(outfilelist):
+                raise RuntimeError('Internal data structures broken.')
+            exe_file = os.path.join(self.environment.get_build_dir(), self.get_target_filename(exe))
+            base_args = generator.get_arglist()
+            for i in range(len(infilelist)):
+                infilename = os.path.join(self.build_to_src, infilelist[i])
+                outfilename = os.path.join(self.get_target_dir(target), outfilelist[i])
+                args = [x.replace("@INPUTNAME@", infilename).replace('@OUTPUTNAME@', outfilename)\
+                        for x in base_args]
+                cmdlist = [exe_file] + args
+                build = 'build %s: CUSTOM_COMMAND %s | %s\n' % \
+                (ninja_quote(outfilename), ninja_quote(infilename), ninja_quote(self.get_target_filename(exe)))
+                command = ' COMMAND = %s\n\n' % \
+                ' '.join(["'%s'" % ninja_quote(i) for i in cmdlist])
+                outfile.write(build)
+                outfile.write(command)
+
     def generate_single_compile(self, target, outfile, src, is_generated=False):
         compiler = self.get_compiler_for_source(src)
         commands = self.generate_basic_compiler_flags(target, compiler)

interpreter.py

@@ -50,6 +50,9 @@ class Generator(InterpreterObject):
         self.methods.update({'process' : self.process_method})
         self.process_kwargs(kwargs)
     
+    def get_exe(self):
+        return self.exe
+
     def process_kwargs(self, kwargs):
         if 'arguments' not in kwargs:
             raise InvalidArguments('Generator must have "arguments" keyword argument.')
@@ -90,6 +93,9 @@ class Generator(InterpreterObject):
         [gl.add_file(a) for a in args]
         return gl
 
+    def get_arglist(self):
+        return self.arglist
+
 class GeneratedList(InterpreterObject):
     def __init__(self, generator):
         InterpreterObject.__init__(self)

test cases/30 pipeline/meson.build

@@ -9,3 +9,5 @@ arguments : ['@INPUTNAME@', '@OUTPUTNAME@'])
 generated = gen.process('input_src.dat')
 
 e2 = executable('prog', 'prog.c', gen_src : generated)
+
+add_test('pipelined', e2)