From 65be7de7aca4bdac05e0acf68ec86a351e779839 Mon Sep 17 00:00:00 2001
From: Boris Kolpackov <boris@codesynthesis.com>
Date: Wed, 18 Mar 2020 07:19:41 +0200
Subject: Add $visibility(<variable>) function for querying variable visibility

---
 libbuild2/functions-builtin.cxx | 15 +++++++++++++++
 libbuild2/variable.cxx          | 18 +++++++++---------
 libbuild2/variable.hxx          | 10 ++++++++--
 3 files changed, 32 insertions(+), 11 deletions(-)

diff --git a/libbuild2/functions-builtin.cxx b/libbuild2/functions-builtin.cxx
index c4f0314..4e28741 100644
--- a/libbuild2/functions-builtin.cxx
+++ b/libbuild2/functions-builtin.cxx
@@ -27,6 +27,21 @@ namespace build2
       return (*s)[convert<string> (move (name))].defined ();
     };
 
+    // Return variable visibility if it exists and NULL otherwise.
+    //
+    f["visibility"] = [](const scope* s, names name)
+    {
+      if (s == nullptr)
+        fail << "visibility() called out of scope" << endf;
+
+      const variable* var (
+        s->ctx.var_pool.find (convert<string> (move (name))));
+
+      return (var != nullptr
+              ? optional<string> (to_string (var->visibility))
+              : nullopt);
+    };
+
     f["type"] = [](value* v) {return v->type != nullptr ? v->type->name : "";};
     f["null"]  = [](value* v) {return v->null;};
     f["empty"] = [](value* v)  {return v->null || v->empty ();};
diff --git a/libbuild2/variable.cxx b/libbuild2/variable.cxx
index 0460344..7b55357 100644
--- a/libbuild2/variable.cxx
+++ b/libbuild2/variable.cxx
@@ -15,21 +15,21 @@ namespace build2
 {
   // variable_visibility
   //
-  ostream&
-  operator<< (ostream& o, variable_visibility v)
+  string
+  to_string (variable_visibility v)
   {
-    const char* s (nullptr);
+    string r;
 
     switch (v)
     {
-    case variable_visibility::normal:  s = "normal";       break;
-    case variable_visibility::project: s = "project";      break;
-    case variable_visibility::scope:   s = "scope";        break;
-    case variable_visibility::target:  s = "target";       break;
-    case variable_visibility::prereq:  s = "prerequisite"; break;
+    case variable_visibility::normal:  r = "normal";       break;
+    case variable_visibility::project: r = "project";      break;
+    case variable_visibility::scope:   r = "scope";        break;
+    case variable_visibility::target:  r = "target";       break;
+    case variable_visibility::prereq:  r = "prerequisite"; break;
     }
 
-    return o << s;
+    return r;
   }
 
   // value
diff --git a/libbuild2/variable.hxx b/libbuild2/variable.hxx
index 071cb5f..b293215 100644
--- a/libbuild2/variable.hxx
+++ b/libbuild2/variable.hxx
@@ -136,8 +136,14 @@ namespace build2
   }
 #endif
 
-  LIBBUILD2_SYMEXPORT ostream&
-  operator<< (ostream&, variable_visibility);
+  LIBBUILD2_SYMEXPORT string
+  to_string (variable_visibility);
+
+  inline ostream&
+  operator<< (ostream& o, variable_visibility v)
+  {
+    return o << to_string (v);
+  }
 
   // variable
   //
-- 
cgit v1.1