[gnome-builder/wip/gtk4-port] plugins/meson: add some helpers to build system

[Christian Hergert <chergert src gnome org>]

commit 7d74b7edae4c4337f7984a386cebf536c2f0ddd1
Author: Christian Hergert <chergert redhat com>
Date:   Thu Jun 23 01:16:23 2022 -0700

    plugins/meson: add some helpers to build system
    
    We use these in other build systems too, and they can cleanup the pipeline
    code and ensure we have the same value in different places.

 src/plugins/meson/gbp-meson-build-system.c | 113 +++++++++++++++++++++++++++--
 src/plugins/meson/gbp-meson-build-system.h |   8 +-
 2 files changed, 112 insertions(+), 9 deletions(-)
---
diff --git a/src/plugins/meson/gbp-meson-build-system.c b/src/plugins/meson/gbp-meson-build-system.c
index ee7dfd18e..3f850b206 100644
--- a/src/plugins/meson/gbp-meson-build-system.c
+++ b/src/plugins/meson/gbp-meson-build-system.c
@@ -20,8 +20,11 @@
 
 #define G_LOG_DOMAIN "gbp-meson-build-system"
 
+#include "config.h"
+
 #include <glib/gi18n.h>
 #include <json-glib/json-glib.h>
+#include <string.h>
 
 #include "gbp-meson-build-system.h"
 #include "gbp-meson-build-target.h"
@@ -29,20 +32,20 @@
 
 struct _GbpMesonBuildSystem
 {
-  IdeObject           parent_instance;
-  GFile              *project_file;
-  IdeCompileCommands *compile_commands;
-  GFileMonitor       *monitor;
-  gchar              *project_version;
-  gchar             **languages;
+  IdeObject            parent_instance;
+  GFile               *project_file;
+  IdeCompileCommands  *compile_commands;
+  GFileMonitor        *monitor;
+  char                *project_version;
+  char               **languages;
 };
 
 static void async_initable_iface_init (GAsyncInitableIface     *iface);
 static void build_system_iface_init   (IdeBuildSystemInterface *iface);
 
 G_DEFINE_FINAL_TYPE_WITH_CODE (GbpMesonBuildSystem, gbp_meson_build_system, IDE_TYPE_OBJECT,
-                         G_IMPLEMENT_INTERFACE (G_TYPE_ASYNC_INITABLE, async_initable_iface_init)
-                         G_IMPLEMENT_INTERFACE (IDE_TYPE_BUILD_SYSTEM, build_system_iface_init))
+                               G_IMPLEMENT_INTERFACE (G_TYPE_ASYNC_INITABLE, async_initable_iface_init)
+                               G_IMPLEMENT_INTERFACE (IDE_TYPE_BUILD_SYSTEM, build_system_iface_init))
 
 enum {
   PROP_0,
@@ -983,3 +986,97 @@ gbp_meson_build_system_get_languages (GbpMesonBuildSystem *self)
 
   return (const gchar * const *)self->languages;
 }
+
+char *
+gbp_meson_build_system_get_project_dir (GbpMesonBuildSystem *self)
+{
+  g_autoptr(GFile) workdir = NULL;
+  g_autofree char *base = NULL;
+  IdeContext *context;
+
+  g_return_val_if_fail (GBP_IS_MESON_BUILD_SYSTEM (self), NULL);
+
+  context = ide_object_get_context (IDE_OBJECT (self));
+  workdir = ide_context_ref_workdir (context);
+
+  if (self->project_file == NULL)
+    return g_strdup (g_file_peek_path (workdir));
+
+  base = g_file_get_basename (self->project_file);
+
+  if (strcasecmp (base, "meson.build") == 0)
+    {
+      g_autoptr(GFile) parent = g_file_get_parent (self->project_file);
+      return g_file_get_path (parent);
+    }
+
+  return g_file_get_path (self->project_file);
+}
+
+char *
+gbp_meson_build_system_locate_meson (GbpMesonBuildSystem *self,
+                                     IdePipeline         *pipeline)
+{
+  IdeConfig *config = NULL;
+
+  g_return_val_if_fail (!self || GBP_IS_MESON_BUILD_SYSTEM (self), NULL);
+  g_return_val_if_fail (!pipeline || IDE_IS_PIPELINE (pipeline), NULL);
+
+  if (pipeline != NULL && config == NULL)
+    config = ide_pipeline_get_config (pipeline);
+
+  /* First check MESON=path override in IdeConfig */
+  if (config != NULL)
+    {
+      const char *envvar = ide_config_getenv (config, "MESON");
+
+      if (envvar != NULL)
+        return g_strdup (envvar);
+    }
+
+  /* Next see if the pipeline or one of it's extensions has Meson */
+  if (pipeline != NULL)
+    {
+      if (ide_pipeline_contains_program_in_path (pipeline, "meson", NULL))
+        return g_strdup ("meson");
+    }
+
+  /* Fallback to "meson" and hope for the best */
+  return g_strdup ("meson");
+}
+
+char *
+gbp_meson_build_system_locate_ninja (GbpMesonBuildSystem *self,
+                                     IdePipeline         *pipeline)
+{
+  IdeConfig *config = NULL;
+
+  g_return_val_if_fail (!self || GBP_IS_MESON_BUILD_SYSTEM (self), NULL);
+  g_return_val_if_fail (!pipeline || IDE_IS_PIPELINE (pipeline), NULL);
+
+  if (pipeline != NULL && config == NULL)
+    config = ide_pipeline_get_config (pipeline);
+
+  /* First check NINJA=path override in IdeConfig */
+  if (config != NULL)
+    {
+      const char *envvar = ide_config_getenv (config, "NINJA");
+
+      if (envvar != NULL)
+        return g_strdup (envvar);
+    }
+
+  if (pipeline != NULL)
+    {
+      static const char *known_aliases[] = { "ninja", "ninja-build" };
+
+      for (guint i = 0; i < G_N_ELEMENTS (known_aliases); i++)
+        {
+          if (ide_pipeline_contains_program_in_path (pipeline, known_aliases[i], NULL))
+            return g_strdup (known_aliases[i]);
+        }
+    }
+
+  /* Fallback to "ninja" and hope for the best */
+  return g_strdup ("ninja");
+}
diff --git a/src/plugins/meson/gbp-meson-build-system.h b/src/plugins/meson/gbp-meson-build-system.h
index 5cb726ff3..bd0f57ece 100644
--- a/src/plugins/meson/gbp-meson-build-system.h
+++ b/src/plugins/meson/gbp-meson-build-system.h
@@ -27,6 +27,12 @@ G_BEGIN_DECLS
 #define GBP_TYPE_MESON_BUILD_SYSTEM (gbp_meson_build_system_get_type())
 
 G_DECLARE_FINAL_TYPE (GbpMesonBuildSystem, gbp_meson_build_system, GBP, MESON_BUILD_SYSTEM, IdeObject)
-const gchar * const * gbp_meson_build_system_get_languages (GbpMesonBuildSystem *self);
+
+const gchar * const *gbp_meson_build_system_get_languages   (GbpMesonBuildSystem *self);
+char                *gbp_meson_build_system_get_project_dir (GbpMesonBuildSystem *self);
+char                *gbp_meson_build_system_locate_meson    (GbpMesonBuildSystem *self,
+                                                             IdePipeline         *pipeline);
+char                *gbp_meson_build_system_locate_ninja    (GbpMesonBuildSystem *self,
+                                                             IdePipeline         *pipeline);
 
 G_END_DECLS