CODEWITHSUNDEEP
stringantreplacematching
Sabrina
Sabrina

Reputation: 11

ant - how to comment all lines except those matching a specific string

I would like to comment all lines of a SQL script except those containing the string TABLE1 (case sensitive) and - if possible - using only a single ant task (replaceregexp?). Ideally, the comment (starting with "--") and blank lines should be ignored but if not this is not so important.

Ex: Initial file

CREATE TABLE TEST (TEST_ID VARCHAR(255) NOT NULL, TEST_NAME VARCHAR(255));
CREATE TABLE LICENSE (ID BIGINT NOT NULL GENERATED BY DEFAULT AS IDENTITY, PRIMARY KEY (ID));

delete from TEST2 where
    ID = 'whatever'
;

delete from TEST3 where
    ENV = 'whatelse'
;

UPDATE TEST1 SET VERSION = '1.0';

Final file

-- CREATE TABLE TEST (TEST_ID VARCHAR(255) NOT NULL, TEST_NAME VARCHAR(255));
-- CREATE TABLE LICENSE (ID BIGINT NOT NULL GENERATED BY DEFAULT AS IDENTITY, PRIMARY KEY (ID));

-- delete from TEST2 where
--  ID = 'whatever'
-- ;

-- delete from TEST3 where
--  ENV = 'whatelse'
-- ;

UPDATE TEST1 SET VERSION = '1.0';

The only solutions I have found are those ones: 1. Comment out all lines of the script and then uncomment the lines that matches the string TEST1:

    <replaceregexp file="${sql.file}"
        match="(.*)"
        replace="-- \1"
        byline="true"
    />
    <replaceregexp file="${sql.file}"
        match="^-- (.*TEST1)"
        replace="\1"
        byline="true"
    />

  1. Create a new file that only contains the line I want to keep:

    <copy file="${sql.file}" tofile="${sql.file.bak}">
  <filterchain>
    <linecontains>
      <contains value="TEST1"/>
    </linecontains>
  </filterchain>
</copy>

I am not so happy with both solutions as: Solution #1. uses 2 tasks and updates the same file twice Solution #2. removes the other lines we would like to keep as comment

If anybody has the right answer I take it.

Thanks, Sabrina

Upvotes: 1

Views: 872

Answers (1)

martin clayton
martin clayton

Reputation: 78155

One solution might be

<replaceregexp file="${sql.file}"
     match="(^(?!$))(?!.*TEST1)"
     replace="-- \1"
     byline="true" />

The key to this is that ?! is the "negative look-ahead assertion" - it says a match is found when the string in brackets after the ?! is not found.

Here's an explanation of the pattern:

NODE                     EXPLANATION
--------------------------------------------------------------------------------
  (                        group and capture to \1:
--------------------------------------------------------------------------------
    ^                        the beginning of the string
--------------------------------------------------------------------------------
    (?!                      look ahead to see if there is not:
--------------------------------------------------------------------------------
      $                        before an optional \n, and the end of
                               the string
--------------------------------------------------------------------------------
    )                        end of look-ahead
--------------------------------------------------------------------------------
  )                        end of \1
--------------------------------------------------------------------------------
  (?!                      look ahead to see if there is not:
--------------------------------------------------------------------------------
    .*                       any character except \n (0 or more times
                             (matching the most amount possible))
--------------------------------------------------------------------------------
    TEST1                    'TEST1'
--------------------------------------------------------------------------------
  )                        end of look-ahead

Upvotes: 1

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