Initial support for ad hoc recipes (still work in progress)

1 files changed, 156 insertions, 0 deletions

diff --git a/libbuild2/build/script/script.hxx b/libbuild2/build/script/script.hxx
new file mode 100644
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+++ b/libbuild2/build/script/script.hxx
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+// file      : libbuild2/build/script/script.hxx -*- C++ -*-
+// license   : MIT; see accompanying LICENSE file
+
+#ifndef LIBBUILD2_BUILD_SCRIPT_SCRIPT_HXX
+#define LIBBUILD2_BUILD_SCRIPT_SCRIPT_HXX
+
+#include <libbuild2/types.hxx>
+#include <libbuild2/forward.hxx>
+#include <libbuild2/utility.hxx>
+
+#include <libbuild2/variable.hxx>
+#include <libbuild2/filesystem.hxx> // auto_rmdir
+
+#include <libbuild2/script/script.hxx>
+
+namespace build2
+{
+  namespace build
+  {
+    namespace script
+    {
+      using build2::script::line;
+      using build2::script::line_type;
+      using build2::script::redirect;
+      using build2::script::redirect_type;
+      using build2::script::expr_term;
+      using build2::script::command_expr;
+
+      // Notes:
+      //
+      // - Once parsed, the script can be executed in multiple threads with
+      //   the state (variable values, etc) maintained in the environment.
+      //
+      // - The default script command redirects semantics is 'none' for stdin,
+      //   'merge' into stderr for stdout, and 'pass' for stderr.
+      //
+      class script
+      {
+      public:
+        // Note that the variables are not pre-entered into a pool during the
+        // parsing phase, so the line variable pointers are NULL.
+        //
+        build2::script::lines lines;
+
+        // Referenced ordinary (non-special) variables.
+        //
+        // Used for the script semantics change tracking. The variable list is
+        // filled during the pre-parsing phase and is checked against during
+        // the execution phase. If during execution some non-script-local
+        // variable is not found in the list (may happen for a computed name),
+        // then the execution fails since the script semantics may not be
+        // properly tracked (the variable value change will not trigger the
+        // target rebuild).
+        //
+        small_vector<string, 2> vars; // 2 for command and options.
+
+        // True if script references the $~ special variable.
+        //
+        bool temp_dir = false;
+
+        location start_loc;
+        location end_loc;
+      };
+
+      class environment: public build2::script::environment
+      {
+      public:
+        using target_type = build2::target;
+
+        environment (action, const target_type&, bool temp_dir);
+
+        environment (environment&&) = delete;
+        environment (const environment&) = delete;
+        environment& operator= (environment&&) = delete;
+        environment& operator= (const environment&) = delete;
+
+      public:
+        // Primary target this environment is for.
+        //
+        const target_type& target;
+
+        // Script-local variable pool and map.
+        //
+        // Note that if we lookup the variable by passing name as a string,
+        // then it will be looked up in the wrong pool.
+        //
+        variable_pool var_pool;
+        variable_map vars;
+
+        // Temporary directory for the script run.
+        //
+        // Currently this directory is removed regardless of the script
+        // execution success or failure. Later, to help with troubleshooting,
+        // we may invent an option that suppresses the removal of temporary
+        // files in general.
+        //
+        // This directory is available to the user via the $~ special
+        // variable. Note, however, that the following filesystem entry
+        // prefixes are reserved:
+        //
+        // stdin*
+        // stdout*
+        // stderr*
+        //
+        auto_rmdir temp_dir;
+
+        virtual void
+        set_variable (string&& name,
+                      names&&,
+                      const string& attrs,
+                      const location&) override;
+
+        virtual void
+        create_temp_dir () override;
+
+        // Variables.
+        //
+      public:
+        // Lookup the variable starting from this environment, then the
+        // primary target, and then outer buildfile scopes.
+        //
+        using lookup_type = build2::lookup;
+
+        lookup_type
+        lookup (const variable&) const;
+
+        lookup_type
+        lookup (const string&) const;
+
+        // As above but only look for buildfile variables.
+        //
+        lookup_type
+        lookup_in_buildfile (const string&) const;
+
+        // Return a value suitable for assignment. If the variable does not
+        // exist in this environment's variable map, then a new one with the
+        // NULL value is added and returned. Otherwise the existing value is
+        // returned.
+        //
+        value&
+        assign (const variable& var) {return vars.assign (var);}
+
+        // Return a value suitable for append/prepend. If the variable does
+        // not exist in this environment's variable map, then outer scopes are
+        // searched for the same variable. If found then a new variable with
+        // the found value is added to the environment and returned. Otherwise
+        // this function proceeds as assign() above.
+        //
+        value&
+        append (const variable&);
+      };
+    }
+  }
+}
+
+#endif // LIBBUILD2_BUILD_SCRIPT_SCRIPT_HXX