Builtin: support shift built-in

7 files changed, 193 insertions, 0 deletions

diff --git a/src/builtins/shift_builtin.cpp b/src/builtins/shift_builtin.cpp
new file mode 100644
index 0000000..c78c6ae
--- /dev/null
+++ b/src/builtins/shift_builtin.cpp
@@ -0,0 +1,44 @@
+/*
+   Please use git log for copyright holder and year information
+
+   This file is part of libbash.
+
+   libbash is free software: you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation, either version 2 of the License, or
+   (at your option) any later version.
+
+   libbash is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with libbash.  If not, see <http://www.gnu.org/licenses/>.
+*/
+///
+/// \file shift_builtin.h
+/// \brief implementation for the shift builtin
+///
+#include "builtins/shift_builtin.h"
+
+#include <boost/lexical_cast.hpp>
+
+#include "builtins/builtin_exceptions.h"
+#include "core/exceptions.h"
+#include "core/interpreter.h"
+
+int shift_builtin::exec(const std::vector<std::string>& bash_args)
+{
+  int shift_number = 1;
+
+  if(!bash_args.empty())
+  {
+    if(bash_args.size() != 1)
+      throw libbash::illegal_argument_exception("shift: the number of arguments should be 1");
+
+    shift_number = boost::lexical_cast<int>(bash_args[0]);
+  }
+
+  return _walker.shift(shift_number);
+}
diff --git a/src/builtins/shift_builtin.h b/src/builtins/shift_builtin.h
new file mode 100644
index 0000000..c413380
--- /dev/null
+++ b/src/builtins/shift_builtin.h
@@ -0,0 +1,35 @@
+/*
+   Please use git log for copyright holder and year information
+
+   This file is part of libbash.
+
+   libbash is free software: you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation, either version 2 of the License, or
+   (at your option) any later version.
+
+   libbash is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with libbash.  If not, see <http://www.gnu.org/licenses/>.
+*/
+///
+/// \file shift_builtin.h
+/// \brief implementation for the shift builtin
+///
+#ifndef LIBBASH_BUILTINS_SHIFT_BUILTIN_H_
+#define LIBBASH_BUILTINS_SHIFT_BUILTIN_H_
+
+#include "cppbash_builtin.h"
+
+class shift_builtin : public virtual cppbash_builtin
+{
+public:
+  BUILTIN_CONSTRUCTOR(shift)
+  virtual int exec(const std::vector<std::string>& );
+};
+
+#endif
diff --git a/src/builtins/tests/shift_tests.cpp b/src/builtins/tests/shift_tests.cpp
new file mode 100644
index 0000000..8625a6c
--- /dev/null
+++ b/src/builtins/tests/shift_tests.cpp
@@ -0,0 +1,69 @@
+/*
+   Please use git log for copyright holder and year information
+
+   This file is part of libbash.
+
+   libbash is free software: you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation, either version 2 of the License, or
+   (at your option) any later version.
+
+   libbash is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with libbash.  If not, see <http://www.gnu.org/licenses/>.
+*/
+///
+/// \file shift_tests.cpp
+/// \brief series of unit tests for shift builtin
+///
+#include <boost/lexical_cast.hpp>
+#include <gtest/gtest.h>
+
+#include "core/exceptions.h"
+#include "core/interpreter.h"
+#include "cppbash_builtin.h"
+
+TEST(shift_builtin_test, bad_argument)
+{
+  interpreter walker;
+  std::map<unsigned, std::string> values = {{1, "1"}, {2, "2"}, {3, "3"}};
+  walker.define("*", values);
+
+  EXPECT_NE(0, cppbash_builtin::exec("shift", {"-1"}, std::cout, std::cerr, std::cin, walker));
+  EXPECT_NE(0, cppbash_builtin::exec("shift", {"4"}, std::cout, std::cerr, std::cin, walker));
+  EXPECT_THROW(cppbash_builtin::exec("shift", {"1", "2"}, std::cout, std::cerr, std::cin, walker),
+               libbash::illegal_argument_exception);
+  EXPECT_THROW(cppbash_builtin::exec("shift", {"abc"}, std::cout, std::cerr, std::cin, walker),
+               boost::bad_lexical_cast);
+}
+
+TEST(shift_builtin_test, shift_all)
+{
+  interpreter walker;
+  std::map<unsigned, std::string> values = {{1, "1"}, {2, "2"}, {3, "3"}};
+  walker.define("*", values);
+
+  EXPECT_EQ(0, cppbash_builtin::exec("shift", {"3"}, std::cout, std::cerr, std::cin, walker));
+  EXPECT_EQ(0, walker.get_array_length("*"));
+}
+
+TEST(shift_builtin_test, normal)
+{
+  interpreter walker;
+  std::map<unsigned, std::string> values = {{1, "1"}, {2, "2"}, {3, "3"}};
+  walker.define("*", values);
+
+  EXPECT_EQ(0, cppbash_builtin::exec("shift", {"2"}, std::cout, std::cerr, std::cin, walker));
+  EXPECT_EQ(1, walker.get_array_length("*"));
+  EXPECT_STREQ("3", walker.resolve<std::string>("*", 1).c_str());
+
+  walker.define("*", values);
+  EXPECT_EQ(0, cppbash_builtin::exec("shift", {"1"}, std::cout, std::cerr, std::cin, walker));
+  EXPECT_EQ(2, walker.get_array_length("*"));
+  EXPECT_STREQ("2", walker.resolve<std::string>("*", 1).c_str());
+  EXPECT_STREQ("3", walker.resolve<std::string>("*", 2).c_str());
+}
diff --git a/src/core/interpreter.cpp b/src/core/interpreter.cpp
index ed9f626..bd19925 100644
--- a/src/core/interpreter.cpp
+++ b/src/core/interpreter.cpp
@@ -435,3 +435,12 @@ long interpreter::eval_arithmetic(const std::string& expression)
   bash_ast ast(std::stringstream(expression), &bash_ast::parser_arithmetics);
   return ast.interpret_with(*this, &bash_ast::walker_arithmetics);
 }
+
+int interpreter::shift(int shift_number)
+{
+  auto parameters = resolve_variable("*");
+  if(shift_number < 0)
+    return 1;
+
+  return parameters->shift(static_cast<unsigned>(shift_number));
+}
diff --git a/src/core/interpreter.h b/src/core/interpreter.h
index c623e86..3363ae7 100644
--- a/src/core/interpreter.h
+++ b/src/core/interpreter.h
@@ -508,6 +508,11 @@ public:
   /// \return the evaluated result
   long eval_arithmetic(const std::string& expression);
 
+  /// \brief shift the positional parameters to the left by n.
+  /// \param the number to be shifted
+  /// \return zero unless n is greater than $# or less than zero, non-zero otherwise.
+  int shift(int shift_number);
+
   /// \brief perform expansion like ${var//foo/bar}
   /// \param value the value to be expanded
   /// \param pattern the pattern used to match the value
diff --git a/src/core/symbols.hpp b/src/core/symbols.hpp
index c535f8f..5114df1 100644
--- a/src/core/symbols.hpp
+++ b/src/core/symbols.hpp
@@ -33,6 +33,7 @@
 
 #include <boost/variant.hpp>
 #include <boost/lexical_cast.hpp>
+#include <boost/numeric/conversion/cast.hpp>
 
 #include "core/exceptions.h"
 
@@ -234,6 +235,34 @@ public:
   {
     return readonly;
   }
+
+  int shift(unsigned shift_number)
+  {
+    assert(!readonly&&"readonly variables shouldn't be shifted");
+    // Remove this cast after making arithmetic expansion follow POSIX
+    unsigned size = boost::numeric_cast<unsigned>(value.size());
+
+    if(shift_number > size) 
+    {
+      return 1;
+    }
+    else if(shift_number == size)
+    {
+      value.clear();
+    }
+    else
+    {
+      // copy elements
+      for(unsigned i = shift_number + 1; i <= size; ++i)
+        value[i - shift_number] = value[i]; 
+
+      // remove tail elements
+      for(unsigned i = size - shift_number + 1; i <= size; ++i)
+        value.erase(i); 
+    }
+
+    return 0;
+  }
 };
 
 /// \brief the specialized constructor for arrays
diff --git a/src/cppbash_builtin.cpp b/src/cppbash_builtin.cpp
index 52c5c9b..3cf4d18 100644
--- a/src/cppbash_builtin.cpp
+++ b/src/cppbash_builtin.cpp
@@ -38,6 +38,7 @@
 #include "builtins/let_builtin.h"
 #include "builtins/return_builtin.h"
 #include "builtins/printf_builtin.h"
+#include "builtins/shift_builtin.h"
 #include "builtins/shopt_builtin.h"
 #include "builtins/source_builtin.h"
 #include "builtins/unset_builtin.h"
@@ -58,6 +59,7 @@ cppbash_builtin::builtins_type& cppbash_builtin::builtins() {
       {"eval", boost::factory<eval_builtin*>()},
       {"declare", boost::factory<declare_builtin*>()},
       {"source", boost::factory<source_builtin*>()},
+      {"shift", boost::factory<shift_builtin*>()},
       {"shopt", boost::factory<shopt_builtin*>()},
       {"inherit", boost::factory<inherit_builtin*>()},
       {":", boost::factory<true_builtin*>()},