How to insert text after multiline match

Question

I have files like this:

class SomeClass
    extends anotherClass
    with moreClassA
    with moreClassB {
    //do some crazy stuff
}

I'd like to add one more class to it like this:

class SomeClass
    extends anotherClass
    with moreClassA
    with moreClassB 
    with oneMoreClassIwant {
    //do some crazy stuff
}

I tried to use sed for replacing like this:

sed -E "s/(Class SomeClass[A-Za-z \n]+)\\{/\1with OneMoreClassIWant/" tmp.scala

but it doesn't work for multi-line matching.

I also noticed an example from this post but failed to adapt it to my case.

Answer 1

Using any awk:

$ cat tst.awk
{ rec = rec $0 RS }
END {
    old = \
        "class SomeClass" RS\
        "    extends anotherClass" RS\
        "    with moreClassA" RS\
        "    with moreClassB {" RS\
        "    //do some crazy stuff" RS\
        "}"

    new = \
        "class SomeClass" RS\
        "    extends anotherClass" RS\
        "    with moreClassA" RS\
        "    with moreClassB" RS\
        "    with oneMoreClassIwant {" RS\
        "    //do some crazy stuff" RS\
        "}"

    if ( s = index(rec,old) ) {
        rec = substr(rec,1,s-1) new substr(rec,s+length(old))
    }

    printf "%s", rec
}

$ awk -f tst.awk file
class SomeClass
    extends anotherClass
    with moreClassA
    with moreClassB
    with oneMoreClassIwant {
    //do some crazy stuff
}

Answer 2

This seems to work:

xargs -0 < data | sed -z 's/\(class.*\){/\1\n    with anotherMoreClass {/'

or

tr '\n' '\0' < data | sed 's/\(class.*\){/\1\n    with anotherMoreClass {/' | tr '\0' '\n'

You can specify the class name (SomeClass in your case) in this section: \(class.*\) like this:

xargs -0 < data |\
sed -z  's/\(class[[:blank:]]\{1,\}SomeClass.*\){/\1\n    with anotherMoreClass {/'

or

tr '\n' '\0' < data |\
sed 's/\(class[[:blank:]]\{1,\}SomeClass.*\){/\1\n    with anotherMoreClass {/' |\
tr '\0' '\n'