[gentoo-commits] proj/libbash:master commit in: scripts/, src/core/, bashast/, src/core/tests/

["Petteri Räty" <betelgeuse@gentoo.org>]

commit:     5e4a93528fc7b0cfef25f7265b1c308b4a54fded
Author:     Mu Qiao <qiaomuf <AT> gentoo <DOT> org>
AuthorDate: Tue Apr  5 13:29:44 2011 +0000
Commit:     Petteri Räty <betelgeuse <AT> gentoo <DOT> org>
CommitDate: Wed Apr  6 10:07:49 2011 +0000
URL:        http://git.overlays.gentoo.org/gitweb/?p=proj/libbash.git;a=commit;h=5e4a9352

Implement substring expansion

Support substring expansion with string variables. Arrays and special
variables like @, * are not supported yet.

---
 bashast/libbashWalker.g             |   11 ++++++++-
 scripts/var_expansion.ebuild        |   13 +++++++++++
 scripts/var_expansion.ebuild.result |   13 +++++++++++
 src/core/interpreter.h              |   41 +++++++++++++++++++++++++++++++++++
 src/core/tests/interpreter_test.cpp |    6 +++++
 5 files changed, 83 insertions(+), 1 deletions(-)

diff --git a/bashast/libbashWalker.g b/bashast/libbashWalker.g
index ad8e444..e6f4393 100644
--- a/bashast/libbashWalker.g
+++ b/bashast/libbashWalker.g
@@ -86,7 +86,10 @@ var_name returns[std::string libbash_value]
 }:
 	num|name|TIMES|AT;
 
-var_expansion returns[std::string libbash_value]:
+var_expansion returns[std::string libbash_value]
+@declarations {
+	bool use_length;
+}:
 	^(USE_DEFAULT var_name libbash_word=word) {
 		libbash_value = walker->do_default_expansion($var_name.libbash_value, libbash_word);
 	}
@@ -95,6 +98,12 @@ var_expansion returns[std::string libbash_value]:
 	}
 	|^(USE_ALTERNATE var_name libbash_word=word) {
 		libbash_value = walker->do_alternate_expansion($var_name.libbash_value, libbash_word);
+	}
+	|^(OFFSET var_name offset=arithmetics { use_length = false; } (length=arithmetics { use_length = true; })?) {
+		if(use_length)
+			libbash_value = walker->do_substring_expansion($var_name.libbash_value, offset, length);
+		else
+			libbash_value = walker->do_substring_expansion($var_name.libbash_value, offset);
 	};
 
 word returns[std::string libbash_value]:

diff --git a/scripts/var_expansion.ebuild b/scripts/var_expansion.ebuild
index f0ad504..247f512 100644
--- a/scripts/var_expansion.ebuild
+++ b/scripts/var_expansion.ebuild
@@ -9,3 +9,16 @@ FOO6=${EAPI:=hello}
 FOO7=${FOO8:=hello}
 FOO9=${EAPI:+hello}
 FOO10=${NOT_EXIST:+hello}
+FOO11=${FOO9:0}
+FOO12=${FOO9:2}
+FOO13=${FOO9: -2}
+FOO14=${FOO9:100}
+FOO15=${FOO9: -100}
+FOO16=${FOO9:(-5 + 5)}
+FOO17=${NOT_EXIST:0}
+FOO18=${FOO9:0:2}
+FOO19=${FOO9:2:2}
+FOO20=${FOO9: -2:2}
+FOO21=${FOO9:2:100}
+FOO22=${FOO9: -2:100}
+FOO23=${NOT_EXIST:0:2}

diff --git a/scripts/var_expansion.ebuild.result b/scripts/var_expansion.ebuild.result
index 7d2e5ca..2c5c42f 100644
--- a/scripts/var_expansion.ebuild.result
+++ b/scripts/var_expansion.ebuild.result
@@ -2,7 +2,20 @@ EAPI=3
 EAPI4=4
 FOO=3
 FOO10=
+FOO11=hello
+FOO12=llo
+FOO13=lo
+FOO14=
+FOO15=
+FOO16=hello
+FOO17=
+FOO18=he
+FOO19=ll
 FOO2=hello
+FOO20=lo
+FOO21=llo
+FOO22=lo
+FOO23=
 FOO3=123
 FOO4=3
 FOO5=2

diff --git a/src/core/interpreter.h b/src/core/interpreter.h
index aad8f48..cde08ac 100644
--- a/src/core/interpreter.h
+++ b/src/core/interpreter.h
@@ -44,6 +44,18 @@ class interpreter{
   /// \var private::members
   /// \brief global symbol table
   scope members;
+
+  /// \brief calculate the correct offset when offset < 0 and check whether
+  ///        the real offset is in legal range
+  /// \param[in,out] a value/result argument referring to offset
+  /// \param[in] the original string
+  /// \return whether the real offset is in legal range
+  bool get_real_offset(int& offset, const std::string& str)
+  {
+    offset = (offset >= 0? offset : str.size() + offset);
+    return !(offset < 0 || offset >= static_cast<int>(str.size()));
+  }
+
 public:
 
   ///
@@ -444,5 +456,34 @@ public:
   {
     return (is_unset_or_null(name)? "" : value);
   }
+
+  /// \brief perform substring expansion
+  /// \param the offset of the substring
+  /// \return the expansion result
+  const std::string do_substring_expansion(const std::string& name,
+                                           int offset)
+  {
+    std::string value = resolve<std::string>(name);
+    if(!get_real_offset(offset, value))
+      return "";
+    return value.substr(offset);
+  }
+
+  /// \brief perform substring expansion
+  /// \param the offset of the substring
+  /// \param the length of the substring
+  /// \return the expansion result
+  const std::string do_substring_expansion(const std::string& name,
+                                           int offset,
+                                           int length)
+  {
+    if(length < 0)
+      throw interpreter_exception("length of substring expression should be greater or equal to zero");
+    std::string value = resolve<std::string>(name);
+    if(!get_real_offset(offset, value))
+      return "";
+    return value.substr(offset, length);
+  }
+
 };
 #endif

diff --git a/src/core/tests/interpreter_test.cpp b/src/core/tests/interpreter_test.cpp
index 2d46e62..6cc2df9 100644
--- a/src/core/tests/interpreter_test.cpp
+++ b/src/core/tests/interpreter_test.cpp
@@ -90,3 +90,9 @@ TEST(interpreter, set_string_value)
                interpreter_exception);
   EXPECT_STREQ("hi", walker.resolve<string>("astring_ro").c_str());
 }
+
+TEST(interperter, substring_expansion_exception)
+{
+  interpreter walker;
+  EXPECT_THROW(walker.do_substring_expansion("", 0, -1), interpreter_exception);
+}