read line in batch file without for loop

Question

I have a xml file with below tags:

<param>
  <name>date</name>
  <Value>20010202</Value>
</param>

I have many such tags in a file. I need to read this file through a batch and update the value of date to a string where name tag contains "date". I have written some code in batch to replace the date (no matter where it is found in complete file) to the desired string. My code is as below:

for /f "tokens=1,* delims=]" %%K in ('"type "example.xml"|find /n /v """') do (
set "line=%%L"
if defined line (
  call set "line=echo.%%line:20010202=desiredString%%"
  for /f "delims=" %%C in ('"echo."%%line%%""') do %%~C
  ) else echo.
) >> "example.tmp"

But I need to perform a check that replaced date should be the value tag for name tag as "date". I want to perform a check inside for loop and and then read next line if current line is matching.

How can I read a line inside for loop and have a check of if condition over it in batch file?

Answer 1

I suppose you could write a solution using pure batch, but it will likely be slow and brittle. By brittle I mean that the XML could be reformatted in a logically equivalent manner, yet break your code. Batch is probably one of the worst languages you could use to manipulate XML.

Ideally you should use a command line tool that is designed explicitly to process XML. Alternatively you could use any language or tool that supports regular expression search and replace. Some options - VBScript, JScript, gnu sed for Windows, Powershell ... the list goes on.

I have written a hybrid batch/JScript REPL.BAT utility that provides an easy way for batch to perform regex search and replace on text files. It is quite fast, much faster than any pure batch solution.

Below is a simple solution using my REPL.BAT utility:

@echo off
setlocal
set "file=example.xml"
set "oldDate=20010202"
set "newDate=20130123"
set "search=(<param>\s*<name>date</name>\s*<Value>)%oldDate%(</Value>\s*</param>)"
type "%file%"|repl "%search%" "$1%newDate%$2" m >"%file%.new"
move /y "%file%.new" "%file%" >nul

Here is the REPL.BAT utility. Full documentation is embedded within the script.

@if (@X)==(@Y) @end /* Harmless hybrid line that begins a JScript comment

::************ Documentation ***********
:::
:::REPL  Search  Replace  [Options  [SourceVar]]
:::REPL  /?
:::
:::  Performs a global search and replace operation on each line of input from
:::  stdin and prints the result to stdout.
:::
:::  Each parameter may be optionally enclosed by double quotes. The double
:::  quotes are not considered part of the argument. The quotes are required
:::  if the parameter contains a batch token delimiter like space, tab, comma,
:::  semicolon. The quotes should also be used if the argument contains a
:::  batch special character like &, |, etc. so that the special character
:::  does not need to be escaped with ^.
:::
:::  If called with a single argument of /? then prints help documentation
:::  to stdout.
:::
:::  Search  - By default this is a case sensitive JScript (ECMA) regular
:::            expression expressed as a string.
:::
:::            JScript syntax documentation is available at
:::            http://msdn.microsoft.com/en-us/library/ae5bf541(v=vs.80).aspx
:::
:::  Replace - By default this is the string to be used as a replacement for
:::            each found search expression. Full support is provided for
:::            substituion patterns available to the JScript replace method.
:::            A $ literal can be escaped as $$. An empty replacement string
:::            must be represented as "".
:::
:::            Replace substitution pattern syntax is documented at
:::            http://msdn.microsoft.com/en-US/library/efy6s3e6(v=vs.80).aspx
:::
:::  Options - An optional string of characters used to alter the behavior
:::            of REPL. The option characters are case insensitive, and may
:::            appear in any order.
:::
:::            I - Makes the search case-insensitive.
:::
:::            L - The Search is treated as a string literal instead of a
:::                regular expression. Also, all $ found in Replace are
:::                treated as $ literals.
:::
:::            E - Search and Replace represent the name of environment
:::                variables that contain the respective values. An undefined
:::                variable is treated as an empty string.
:::
:::            M - Multi-line mode. The entire contents of stdin is read and
:::                processed in one pass instead of line by line. ^ anchors
:::                the beginning of a line and $ anchors the end of a line.
:::
:::            X - Enables extended substitution pattern syntax with support
:::                for the following escape sequences:
:::
:::                \\     -  Backslash
:::                \b     -  Backspace
:::                \f     -  Formfeed
:::                \n     -  Newline
:::                \r     -  Carriage Return
:::                \t     -  Horizontal Tab
:::                \v     -  Vertical Tab
:::                \xnn   -  Ascii (Latin 1) character expressed as 2 hex digits
:::                \unnnn -  Unicode character expressed as 4 hex digits
:::
:::                Escape sequences are supported even when the L option is used.
:::
:::            S - The source is read from an environment variable instead of
:::                from stdin. The name of the source environment variable is
:::                specified in the next argument after the option string.
:::

::************ Batch portion ***********
@echo off
if .%2 equ . (
  if "%~1" equ "/?" (
    findstr "^:::" "%~f0" | cscript //E:JScript //nologo "%~f0" "^:::" ""
    exit /b 0
  ) else (
    call :err "Insufficient arguments"
    exit /b 1
  )
)
echo(%~3|findstr /i "[^SMILEX]" >nul && (
  call :err "Invalid option(s)"
  exit /b 1
)
cscript //E:JScript //nologo "%~f0" %*
exit /b 0

:err
>&2 echo ERROR: %~1. Use REPL /? to get help.
exit /b

************* JScript portion **********/
var env=WScript.CreateObject("WScript.Shell").Environment("Process");
var args=WScript.Arguments;
var search=args.Item(0);
var replace=args.Item(1);
var options="g";
if (args.length>2) {
  options+=args.Item(2).toLowerCase();
}
var multi=(options.indexOf("m")>=0);
var srcVar=(options.indexOf("s")>=0);
if (srcVar) {
  options=options.replace(/s/g,"");
}
if (options.indexOf("e")>=0) {
  options=options.replace(/e/g,"");
  search=env(search);
  replace=env(replace);
}
if (options.indexOf("l")>=0) {
  options=options.replace(/l/g,"");
  search=search.replace(/([.^$*+?()[{\\|])/g,"\\$1");
  replace=replace.replace(/\$/g,"$$$$");
}
if (options.indexOf("x")>=0) {
  options=options.replace(/x/g,"");
  replace=replace.replace(/\\\\/g,"\\B");
  replace=replace.replace(/\\b/g,"\b");
  replace=replace.replace(/\\f/g,"\f");
  replace=replace.replace(/\\n/g,"\n");
  replace=replace.replace(/\\r/g,"\r");
  replace=replace.replace(/\\t/g,"\t");
  replace=replace.replace(/\\v/g,"\v");
  replace=replace.replace(/\\x[0-9a-fA-F]{2}|\\u[0-9a-fA-F]{4}/g,
    function($0,$1,$2){
      return String.fromCharCode(parseInt("0x"+$0.substring(2)));
    }
  );
  replace=replace.replace(/\\B/g,"\\");
}
var search=new RegExp(search,options);

if (srcVar) {
  WScript.Stdout.Write(env(args.Item(3)).replace(search,replace));
} else {
  while (!WScript.StdIn.AtEndOfStream) {
    if (multi) {
      WScript.Stdout.Write(WScript.StdIn.ReadAll().replace(search,replace));
    } else {
      WScript.Stdout.WriteLine(WScript.StdIn.ReadLine().replace(search,replace));
    }
  }
}