Add support for 'while' loop in script

8 files changed, 324 insertions, 72 deletions

diff --git a/libbuild2/build/script/parser+command-if.test.testscript b/libbuild2/build/script/parser+command-if.test.testscript
index a18a885..8b19186 100644
--- a/libbuild2/build/script/parser+command-if.test.testscript
+++ b/libbuild2/build/script/parser+command-if.test.testscript
@@ -279,7 +279,7 @@
   cmd
   end
   EOI
-  buildfile:12:1: error: 'end' without preceding 'if'
+  buildfile:12:1: error: 'end' without preceding 'if', 'for', or 'while'
   EOE
 
   : before
diff --git a/libbuild2/build/script/parser+while.test.testscript b/libbuild2/build/script/parser+while.test.testscript
new file mode 100644
index 0000000..5587291
--- /dev/null
+++ b/libbuild2/build/script/parser+while.test.testscript
@@ -0,0 +1,133 @@
+# file      : libbuild2/build/script/parser+while.test.testscript
+# license   : MIT; see accompanying LICENSE file
+
+: while
+:
+{
+  : true
+  :
+  $* <<EOI >>EOO
+  while ($v != "aa")
+    cmd "$v"
+    v = "$(v)a"
+  end
+  EOI
+  ? true
+  cmd ''
+  ? true
+  cmd a
+  ? false
+  EOO
+
+  : false
+  :
+  $* <<EOI >>EOO
+  while ($v == "aa")
+    cmd "$v"
+    v = "$(v)a"
+  end
+  EOI
+  ? false
+  EOO
+
+  : without-command
+  :
+  $* <<EOI 2>>EOE != 0
+  while
+    cmd
+  end
+  EOI
+  buildfile:11:6: error: missing program
+  EOE
+}
+
+: end
+:
+{
+  : without-end
+  :
+  $* <<EOI 2>>EOE != 0
+  while true
+    cmd
+  EOI
+  buildfile:13:1: error: expected closing 'end'
+  EOE
+}
+
+: elif
+:
+{
+  : without-if
+  :
+  $* <<EOI 2>>EOE != 0
+  while false
+    elif true
+      cmd
+    end
+  end
+  EOI
+  buildfile:12:3: error: 'elif' without preceding 'if'
+  EOE
+}
+
+: nested
+:
+{
+  $* -l -r <<EOI >>EOO
+  while ($v != "aa")      # 1
+    cmd1 "$v"             # 2
+    if ($v == "a")        # 3
+      cmd2                # 4
+      while ($v2 != "$v") # 5
+        cmd3              # 6
+        v2=$v
+      end
+    else
+      cmd4                # 7
+    end
+    cmd5                  # 8
+    v = "$(v)a"
+  end
+  EOI
+  ? true # 1 i1
+  cmd1 '' # 2 i1
+  ? false # 3 i1
+  cmd4 # 7 i1
+  cmd5 # 8 i1
+  ? true # 1 i2
+  cmd1 a # 2 i2
+  ? true # 3 i2
+  cmd2 # 4 i2
+  ? true # 5 i2 i1
+  cmd3 # 6 i2 i1
+  ? false # 5 i2 i2
+  cmd5 # 8 i2
+  ? false # 1 i3
+  EOO
+}
+
+: contained
+:
+{
+  : eos
+  :
+  $* <<EOI 2>>EOE != 0
+  while
+  EOI
+  buildfile:12:1: error: expected closing 'end'
+  EOE
+}
+
+: var
+:
+$* <<EOI >>EOO
+while ($v1 != "a")
+  v1 = "$(v1)a"
+  v2 = "$v1"
+end
+cmd $v1
+EOI
+? true
+? false
+cmd a
+EOO
diff --git a/libbuild2/build/script/parser.cxx b/libbuild2/build/script/parser.cxx
index 0614f20..1a7f4e1 100644
--- a/libbuild2/build/script/parser.cxx
+++ b/libbuild2/build/script/parser.cxx
@@ -193,9 +193,22 @@ namespace build2
         }
       }
 
+      // Parse a logical line, handling the flow control constructs
+      // recursively.
+      //
+      // If the flow control construct type is specified, then this line is
+      // assumed to belong to such a construct.
+      //
       void parser::
-      pre_parse_line (token& t, type& tt, bool if_line)
+      pre_parse_line (token& t, type& tt, optional<line_type> fct)
       {
+        // enter: next token is peeked at (type in tt)
+        // leave: newline
+
+        assert (!fct                      ||
+                *fct == line_type::cmd_if ||
+                *fct == line_type::cmd_while);
+
         // Determine the line type/start token.
         //
         line_type lt (
@@ -235,19 +248,25 @@ namespace build2
         case line_type::cmd_elif:
         case line_type::cmd_elifn:
         case line_type::cmd_else:
-        case line_type::cmd_end:
           {
-            if (!if_line)
-            {
+            if (!fct || *fct != line_type::cmd_if)
               fail (t) << lt << " without preceding 'if'";
-            }
+          }
+          // Fall through.
+        case line_type::cmd_end:
+          {
+            if (!fct)
+              fail (t) << lt << " without preceding 'if', 'for', or 'while'";
           }
           // Fall through.
         case line_type::cmd_if:
         case line_type::cmd_ifn:
+        case line_type::cmd_while:
           next (t, tt); // Skip to start of command.
 
-          if (lt == line_type::cmd_if || lt == line_type::cmd_ifn)
+          if (lt == line_type::cmd_if  ||
+              lt == line_type::cmd_ifn ||
+              lt == line_type::cmd_while)
             ++level_;
           else if (lt == line_type::cmd_end)
             --level_;
@@ -287,6 +306,50 @@ namespace build2
 
           pre_parse_if_else (t, tt);
         }
+        else if (lt == line_type::cmd_while)
+        {
+          tt = peek (lexer_mode::first_token);
+
+          pre_parse_while (t, tt);
+        }
+      }
+
+      // Pre-parse the flow control construct block line.
+      //
+      void parser::
+      pre_parse_block_line (token& t, type& tt, line_type bt)
+      {
+        // enter: peeked first token of the line (type in tt)
+        // leave: newline
+
+        const location ll (get_location (peeked ()));
+
+        if (tt == type::eos)
+          fail (ll) << "expected closing 'end'";
+
+        line_type fct; // Flow control type the block type relates to.
+
+        switch (bt)
+        {
+        case line_type::cmd_if:
+        case line_type::cmd_ifn:
+        case line_type::cmd_elif:
+        case line_type::cmd_elifn:
+        case line_type::cmd_else:
+          {
+            fct = line_type::cmd_if;
+            break;
+          }
+        case line_type::cmd_while:
+          {
+            fct = line_type::cmd_while;
+            break;
+          }
+        default: assert(false);
+        }
+
+        pre_parse_line (t, tt, fct);
+        assert (tt == type::newline);
       }
 
       void parser::
@@ -295,8 +358,7 @@ namespace build2
         // enter: peeked first token of next line (type in tt)
         // leave: newline
 
-        // Parse lines until we see closing 'end'. Nested if-else blocks are
-        // handled recursively.
+        // Parse lines until we see closing 'end'.
         //
         for (line_type bt (line_type::cmd_if); // Current block.
              ;
@@ -304,25 +366,21 @@ namespace build2
         {
           const location ll (get_location (peeked ()));
 
-          if (tt == type::eos)
-            fail (ll) << "expected closing 'end'";
-
           // Parse one line. Note that this one line can still be multiple
-          // lines in case of if-else. In this case we want to view it as
-          // cmd_if, not cmd_end. Thus remember the start position of the
-          // next logical line.
+          // lines in case of a flow control construct. In this case we want
+          // to view it as cmd_if, not cmd_end. Thus remember the start
+          // position of the next logical line.
           //
           size_t i (script_->body.size ());
 
-          pre_parse_line (t, tt, true /* if_line */);
-          assert (tt == type::newline);
+          pre_parse_block_line (t, tt, bt);
 
           line_type lt (script_->body[i].type);
 
           // First take care of 'end'.
           //
           if (lt == line_type::cmd_end)
-            return;
+            break;
 
           // Check if-else block sequencing.
           //
@@ -346,6 +404,25 @@ namespace build2
         }
       }
 
+      void parser::
+      pre_parse_while (token& t, type& tt)
+      {
+        // enter: peeked first token of next line (type in tt)
+        // leave: newline
+
+        // Parse lines until we see closing 'end'.
+        //
+        for (;; tt = peek (lexer_mode::first_token))
+        {
+          size_t i (script_->body.size ());
+
+          pre_parse_block_line (t, tt, line_type::cmd_while);
+
+          if (script_->body[i].type == line_type::cmd_end)
+            break;
+        }
+      }
+
       command_expr parser::
       parse_command_line (token& t, type& tt)
       {
@@ -946,7 +1023,7 @@ namespace build2
         // Note that we rely on "small function object" optimization here.
         //
         auto exec_cmd = [this] (token& t, build2::script::token_type& tt,
-                                size_t li,
+                                const iteration_index* ii, size_t li,
                                 bool single,
                                 const location& ll)
         {
@@ -958,7 +1035,7 @@ namespace build2
           command_expr ce (
             parse_command_line (t, static_cast<token_type&> (tt)));
 
-          runner_->run (*environment_, ce, li, ll);
+          runner_->run (*environment_, ce, ii, li, ll);
         };
 
         exec_lines (s.body, exec_cmd);
@@ -1009,13 +1086,13 @@ namespace build2
 
         auto exec_cmd = [this, &data] (token& t,
                                        build2::script::token_type& tt,
-                                       size_t li,
+                                       const iteration_index* ii, size_t li,
                                        bool /* single */,
                                        const location& ll)
         {
           // Note that we never reset the line index to zero (as we do in
-          // execute_body()) assuming that there are some script body
-          // commands to follow.
+          // execute_body()) assuming that there are some script body commands
+          // to follow.
           //
           if (tt == type::word && t.value == "depdb")
           {
@@ -1128,7 +1205,7 @@ namespace build2
                 info (rt[0].location ()) << "depdb preamble ends here";
             }
 
-            runner_->run (*environment_, ce, li, ll);
+            runner_->run (*environment_, ce, ii, li, ll);
           }
         };
 
@@ -1191,20 +1268,22 @@ namespace build2
           apply_value_attributes (&var, lhs, move (rhs), kind);
         };
 
-        auto exec_if = [this] (token& t, build2::script::token_type& tt,
-                               size_t li,
-                               const location& ll)
+        auto exec_cond = [this] (token& t, build2::script::token_type& tt,
+                                 const iteration_index* ii, size_t li,
+                                 const location& ll)
         {
           command_expr ce (
             parse_command_line (t, static_cast<token_type&> (tt)));
 
-          // Assume if-else always involves multiple commands.
+          // Assume a flow control construct always involves multiple
+          // commands.
           //
-          return runner_->run_if (*environment_, ce, li, ll);
+          return runner_->run_cond (*environment_, ce, ii, li, ll);
         };
 
         build2::script::parser::exec_lines (begin, end,
-                                            exec_set, exec_cmd, exec_if,
+                                            exec_set, exec_cmd, exec_cond,
+                                            nullptr /* iteration_index */,
                                             environment_->exec_line,
                                             &environment_->var_pool);
       }
@@ -2145,10 +2224,12 @@ namespace build2
             istringstream iss;
             if (prog)
             {
+              // Note: depdb is disallowed inside flow control constructs.
+              //
               string s;
               build2::script::run (*environment_,
                                    cmd,
-                                   li,
+                                   nullptr /* iteration_index */, li,
                                    ll,
                                    !file ? &s : nullptr);
 
diff --git a/libbuild2/build/script/parser.hxx b/libbuild2/build/script/parser.hxx
index 932cbad..987ed1f 100644
--- a/libbuild2/build/script/parser.hxx
+++ b/libbuild2/build/script/parser.hxx
@@ -65,11 +65,18 @@ namespace build2
         pre_parse_script ();
 
         void
-        pre_parse_line (token&, token_type&, bool if_line = false);
+        pre_parse_line (token&, token_type&,
+                        optional<line_type> flow_control_type = nullopt);
+
+        void
+        pre_parse_block_line (token&, token_type&, line_type block_type);
 
         void
         pre_parse_if_else (token&, token_type&);
 
+        void
+        pre_parse_while (token&, token_type&);
+
         command_expr
         parse_command_line (token&, token_type&);
 
@@ -367,13 +374,13 @@ namespace build2
         //
         line* save_line_;
 
-        // The if-else nesting level (and in the future for other flow
-        // control constructs).
+        // The flow control constructs nesting level.
         //
-        // Maintained during pre-parsing and is incremented when the cmd_if or
-        // cmd_ifn lines are encountered, which in particular means that it is
-        // already incremented by the time the if-condition expression is
-        // pre-parsed. Decremented when the cmd_end line is encountered.
+        // Maintained during pre-parsing and is incremented when flow control
+        // construct condition lines are encountered, which in particular
+        // means that it is already incremented by the time the condition
+        // expression is pre-parsed. Decremented when the cmd_end line is
+        // encountered.
         //
         size_t level_ = 0;
 
diff --git a/libbuild2/build/script/parser.test.cxx b/libbuild2/build/script/parser.test.cxx
index 5808015..f8c2696 100644
--- a/libbuild2/build/script/parser.test.cxx
+++ b/libbuild2/build/script/parser.test.cxx
@@ -29,7 +29,9 @@ namespace build2
       class print_runner: public runner
       {
       public:
-        print_runner (bool line): line_ (line) {}
+        print_runner (bool line, bool iterations):
+            line_ (line),
+            iterations_ (iterations) {}
 
         virtual void
         enter (environment&, const location&) override {}
@@ -37,27 +39,27 @@ namespace build2
         virtual void
         run (environment&,
              const command_expr& e,
-             size_t i,
+             const iteration_index* ii, size_t i,
              const location&) override
         {
           cout << e;
 
-          if (line_)
-            cout << " # " << i;
+          if (line_ || iterations_)
+            print_line_info (ii, i);
 
           cout << endl;
         }
 
         virtual bool
-        run_if (environment&,
-                const command_expr& e,
-                size_t i,
-                const location&) override
+        run_cond (environment&,
+                  const command_expr& e,
+                  const iteration_index* ii, size_t i,
+                  const location&) override
         {
           cout << "? " << e;
 
-          if (line_)
-            cout << " # " << i;
+          if (line_ || iterations_)
+            print_line_info (ii, i);
 
           cout << endl;
 
@@ -68,12 +70,32 @@ namespace build2
         leave (environment&, const location&) override {}
 
       private:
+        void
+        print_line_info (const iteration_index* ii, size_t i) const
+        {
+          cout << " #";
+
+          if (line_)
+            cout << ' ' << i;
+
+          if (iterations_ && ii != nullptr)
+          {
+            string s;
+            for (const iteration_index* i (ii); i != nullptr; i = i->prev)
+              s.insert (0, " i" + to_string (i->index));
+
+            cout << s;
+          }
+        }
+
+      private:
         bool line_;
+        bool iterations_;
       };
 
       // Usages:
       //
-      // argv[0] [-l]
+      // argv[0] [-l] [-r]
       // argv[0] -b [-t]
       // argv[0] -d [-t]
       // argv[0] -q
@@ -99,6 +121,9 @@ namespace build2
       // -l
       //    Print the script line number for each executed expression.
       //
+      // -r
+      //    Print the loop iteration numbers for each executed expression.
+      //
       // -b
       //    Dump the parsed script body to stdout.
       //
@@ -136,6 +161,7 @@ namespace build2
         } m (mode::run);
 
         bool print_line (false);
+        bool print_iterations (false);
         optional<string> diag_name;
         bool temp_dir (false);
 
@@ -145,6 +171,8 @@ namespace build2
 
           if (a == "-l")
             print_line = true;
+          else if (a == "-r")
+            print_iterations = true;
           else if (a == "-b")
             m = mode::body;
           else if (a == "-d")
@@ -170,8 +198,9 @@ namespace build2
           }
         }
 
-        assert (!print_line || m == mode::run);
-        assert (!diag_name  || m == mode::diag);
+        assert (!print_line       || m == mode::run);
+        assert (!print_iterations || m == mode::run);
+        assert (!diag_name        || m == mode::diag);
 
         // Fake build system driver, default verbosity.
         //
@@ -223,7 +252,7 @@ namespace build2
           case mode::run:
             {
               environment e (perform_update_id, tt, s.body_temp_dir);
-              print_runner r (print_line);
+              print_runner r (print_line, print_iterations);
               p.execute_body (ctx.global_scope, ctx.global_scope, e, s, r);
               break;
             }
diff --git a/libbuild2/build/script/runner.cxx b/libbuild2/build/script/runner.cxx
index 51139d4..157fc60 100644
--- a/libbuild2/build/script/runner.cxx
+++ b/libbuild2/build/script/runner.cxx
@@ -96,7 +96,7 @@ namespace build2
       void default_runner::
       run (environment& env,
            const command_expr& expr,
-           size_t li,
+           const iteration_index* ii, size_t li,
            const location& ll)
       {
         if (verb >= 3)
@@ -115,20 +115,21 @@ namespace build2
                               (p.recall.string () == "set" ||
                                p.recall.string () == "exit");
                      }) != expr.end ())
-          build2::script::run (env, expr, li, ll);
+          build2::script::run (env, expr, ii, li, ll);
         else if (verb >= 2)
           text << expr;
       }
 
       bool default_runner::
-      run_if (environment& env,
-              const command_expr& expr,
-              size_t li, const location& ll)
+      run_cond (environment& env,
+                const command_expr& expr,
+                const iteration_index* ii, size_t li,
+                const location& ll)
       {
         if (verb >= 3)
           text << ": ?" << expr;
 
-        return build2::script::run_if (env, expr, li, ll);
+        return build2::script::run_cond (env, expr, ii, li, ll);
       }
     }
   }
diff --git a/libbuild2/build/script/runner.hxx b/libbuild2/build/script/runner.hxx
index 558de9b..0652396 100644
--- a/libbuild2/build/script/runner.hxx
+++ b/libbuild2/build/script/runner.hxx
@@ -35,14 +35,14 @@ namespace build2
         virtual void
         run (environment&,
              const command_expr&,
-             size_t index,
+             const iteration_index*, size_t index,
              const location&) = 0;
 
         virtual bool
-        run_if (environment&,
-                const command_expr&,
-                size_t,
-                const location&) = 0;
+        run_cond (environment&,
+                  const command_expr&,
+                  const iteration_index*, size_t,
+                  const location&) = 0;
 
         // Location is the script end location (for diagnostics, etc).
         //
@@ -52,9 +52,9 @@ namespace build2
 
       // 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 print them at
-      // verbosity level 2 and up.
+      // In dry-run mode don't run the expressions unless they are flow
+      // control construct conditions or execute the set or exit builtins, but
+      // print them at verbosity level 2 and up.
       //
       class default_runner: public runner
       {
@@ -65,14 +65,14 @@ namespace build2
         virtual void
         run (environment&,
              const command_expr&,
-             size_t,
+             const iteration_index*, size_t,
              const location&) override;
 
         virtual bool
-        run_if (environment&,
-                const command_expr&,
-                size_t,
-                const location&) override;
+        run_cond (environment&,
+                  const command_expr&,
+                  const iteration_index*, size_t,
+                  const location&) override;
 
         virtual void
         leave (environment&, const location&) override;
diff --git a/libbuild2/build/script/script.hxx b/libbuild2/build/script/script.hxx
index d0ab139..f8df204 100644
--- a/libbuild2/build/script/script.hxx
+++ b/libbuild2/build/script/script.hxx
@@ -20,12 +20,13 @@ namespace build2
     namespace script
     {
       using build2::script::line;
-      using build2::script::lines;
       using build2::script::line_type;
+      using build2::script::lines;
       using build2::script::redirect;
       using build2::script::redirect_type;
       using build2::script::expr_term;
       using build2::script::command_expr;
+      using build2::script::iteration_index;
       using build2::script::deadline;
       using build2::script::timeout;