1 files changed, 84 insertions, 0 deletions
diff --git a/libbuild2/build/script/runner.hxx b/libbuild2/build/script/runner.hxx
new file mode 100644
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--- /dev/null
+++ b/libbuild2/build/script/runner.hxx
@@ -0,0 +1,84 @@
+// file      : libbuild2/build/script/runner.hxx -*- C++ -*-
+// license   : MIT; see accompanying LICENSE file
+
+#ifndef LIBBUILD2_BUILD_SCRIPT_RUNNER_HXX
+#define LIBBUILD2_BUILD_SCRIPT_RUNNER_HXX
+
+#include <libbuild2/types.hxx>
+#include <libbuild2/utility.hxx>
+
+#include <libbuild2/build/script/script.hxx>
+
+namespace build2
+{
+  namespace build
+  {
+    struct common;
+
+    namespace script
+    {
+      class runner
+      {
+      public:
+        // Location is the script start location (for diagnostics, etc).
+        //
+        virtual void
+        enter (environment&, const location&) = 0;
+
+        // Index is the 1-base index of this command line in the command list.
+        // If it is 0 then it means there is only one command. This
+        // information can be used, for example, to derive file names.
+        //
+        // Location is the start position of this command line in the script.
+        // It can be used in diagnostics.
+        //
+        virtual void
+        run (environment&,
+             const command_expr&,
+             size_t index,
+             const location&) = 0;
+
+        virtual bool
+        run_if (environment&,
+                const command_expr&,
+                size_t,
+                const location&) = 0;
+
+        // Location is the script end location (for diagnostics, etc).
+        //
+        virtual void
+        leave (environment&, const location&) = 0;
+      };
+
+      // Run command expressions.
+      //
+      // In dry-run mode don't run the expressions unless they are if-
+      // conditions or execute the set or exit builtins, but prints them at
+      // verbosity level 2 and up.
+      //
+      class default_runner: public runner
+      {
+      public:
+        virtual void
+        enter (environment&, const location&) override;
+
+        virtual void
+        run (environment&,
+             const command_expr&,
+             size_t,
+             const location&) override;
+
+        virtual bool
+        run_if (environment&,
+                const command_expr&,
+                size_t,
+                const location&) override;
+
+        virtual void
+        leave (environment&, const location&) override;
+      };
+    }
+  }
+}
+
+#endif // LIBBUILD2_BUILD_SCRIPT_RUNNER_HXX