add missing files

git-svn-id: https://svn.apache.org/repos/asf/incubator/couchdb/trunk@687339 13f79535-47bb-0310-9956-ffa450edef68

1 files changed, 147 insertions, 0 deletions

diff --git a/src/couchdb/couch_config_writer.erl b/src/couchdb/couch_config_writer.erl
new file mode 100644
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+++ b/src/couchdb/couch_config_writer.erl
@@ -0,0 +1,147 @@
+% Licensed under the Apache License, Version 2.0 (the "License"); you may not
+% use this file except in compliance with the License.  You may obtain a copy of
+% the License at
+%
+%   http://www.apache.org/licenses/LICENSE-2.0
+%
+% Unless required by applicable law or agreed to in writing, software
+% distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+% WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the
+% License for the specific language governing permissions and limitations under
+% the License.
+
+%% @doc Saves a Key/Value pair to a ini file. The Key consists of a Module
+%%      and Variable combination. If that combination is found in the ini file
+%%      the new value replaces the old value. If only the Module is found the
+%%      Variable and value combination is appended to the Module. If the Module
+%%      does not yet exist in the ini file, it is added and the Variable/Value
+%%      pair is appended.
+%% @see couch_config
+
+-module(couch_config_writer).
+-include("couch_db.hrl").
+
+-export([save_to_file/2]).
+
+%% @spec save_to_file(
+%%           Config::{{Module::string(), Variable::string()}, Value::string()}, 
+%%           File::filename()) -> ok
+%% @doc Saves a Module/Key/Value triple to the ini file File::filename()
+save_to_file({{Module, Variable}, Value}, File) ->
+    
+    ?LOG_DEBUG("saving to file '~s', Congif: '~p'", [File, {{Module, Variable}, Value}]),
+    
+    % open file and create a list of lines
+    {ok, Stream} = file:read_file(File),
+    OldFileContents = binary_to_list(Stream),
+    {ok, Lines} = regexp:split(OldFileContents, "\r\n|\n|\r|\032"),
+    
+    % prepare input variables
+    ModuleName = "[" ++ Module ++ "]",
+    VariableList = Variable,
+    
+    % produce the contents for the config file
+    NewFileContents = 
+    case NewFileContents2 = save_loop({{ModuleName, VariableList}, Value}, Lines, "", "", []) of
+        % we didn't change anything, that means we couldn't find a matching
+        % [ini section] in which case we just append a new one.
+        OldFileContents ->
+            append_new_ini_section({{ModuleName, VariableList}, Value}, OldFileContents);
+        _ ->
+            NewFileContents2
+    end,
+    
+    % do the save, close the config file and get out
+    save_file(File, NewFileContents),
+    file:close(Stream),
+    ok.
+
+%% @doc Iterates over the lines of an ini file and replaces or adds a new
+%%      configuration directive.
+save_loop({{Module, Variable}, Value}, [Line|Rest], OldCurrentModule, Contents, DoneVariables) ->
+
+    % if we find a new [ini section] (Module), save that for reference
+    NewCurrentModule = parse_module(Line, OldCurrentModule),
+
+    % if the current Module is the one we want to change, try to match
+    % each line with the Variable
+    NewContents = case Module of
+        NewCurrentModule ->
+            % see if the current line matches the variable we want to substitute
+            case parse_variable(Line, Variable, Value) of
+                % nope, return original line
+                nomatch ->
+                    DoneVariables2 = DoneVariables,
+                    Line;
+                % got em! return new line
+                NewLine ->
+                    DoneVariables2 = [Variable|DoneVariables],
+                    NewLine
+            end;
+        % if the variable we want to change couldn't be replaced, we append it
+        % in the proper module section
+        OldCurrentModule ->
+            case lists:member(Variable, DoneVariables) of
+                false ->
+                    DoneVariables2 = [Variable|DoneVariables],
+                    Variable ++ "=" ++ Value ++ "\n" ++ Line;
+                true ->
+                    DoneVariables2 = DoneVariables,
+                    Line
+            end;
+        % otherwise we just print out the original line
+        _ ->
+            DoneVariables2 = DoneVariables,
+            Line
+        end,
+    % clumsy way to only append a newline character
+    % if the line is not empty. We need this to not
+    % avoid haveing a newline inserted at the top
+    % of the target file each time we save it.
+    Contents2 = case Contents of "" -> ""; _ -> Contents ++ "\n" end,
+
+    % go to next line
+    save_loop({{Module, Variable}, Value}, Rest, NewCurrentModule, Contents2 ++ NewContents, DoneVariables2);
+    
+save_loop(_Config, [], _OldModule, NewFileContents, _DoneVariable) ->
+    % we're out of new lines, just return the new file's contents
+    NewFileContents.
+
+append_new_ini_section({{ModuleName, Variable}, Value}, OldFileContents) ->
+    OldFileContents ++ "\n\n" ++ ModuleName ++ "\n" ++  Variable ++ "=" ++ Value ++ "\n".
+
+%% @spec parse_module(Lins::string(), OldModule::string()) -> string()
+%% @doc Tries to match a line against a pattern specifying a ini module or 
+%%      section ("[Module]"). Returns OldModule if no match is found.
+parse_module(Line, OldModule) ->
+    case regexp:match(Line, "^\\[([a-zA-Z0-9_-]*)\\]$") of
+        nomatch ->
+            OldModule;
+        {error, Error} ->
+            io:format("ini file regex error module: '~s'~n", [Error]),
+            OldModule;
+        {match, Start, Length} ->
+            string:substr(Line, Start, Length)
+    end.
+
+%% @spec parse_variable(Line::string(), Variable::string(), Value::string()) ->
+%%         string() | nomatch
+%% @doc Tries to match a variable assignment in Line. Returns nomatch if the
+%%      Variable is not found. Returns a new line composed of the Variable and
+%%      Value otherwise.
+parse_variable(Line, Variable, Value) ->
+    case regexp:match(Line, "^" ++ Variable ++ "=") of
+        nomatch ->
+            nomatch;
+        {error, Error}->
+            io:format("ini file regex error variable: '~s'~n", [Error]),
+            nomatch;
+        {match, _Start, _Length} ->
+            Variable ++ "=" ++ Value
+    end.
+
+%% @spec save_file(File::filename(), Contents::string()) -> 
+%%           ok | {error, Reason::string()}
+%% @doc Writes Contents to File
+save_file(File, Contents) ->
+    file:write_file(File, list_to_binary(Contents)).
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