CODEWITHSUNDEEP
regex
zontragon
zontragon

Reputation: 820

how to separate overlapped patterns

I have a header file which contains several struct definitions. I want to extract a spesific struct from this file. For example I need to get only second struct.

typedef struct {
  int a;
  int b;
} first;

typedef struct {
  int x;
 int y;
} second;

Below expression 

...
headerText = headerFile.read()
re.match(r"typedef struct {(.*)} second;", headerText) 
...

returns

int a;
  int b;
} first;

typedef struct {
  int x;
  int y;

How can I get only the second struct? Thanks...

Upvotes: 1

Views: 59

Answers (1)

Anirudha
Anirudha

Reputation: 32807

Use this regex..just replace the second with any other required struct name

[without groups]

Use this regex if you dont want the groups

typedef struct(?!.*?typedef struct).*?\}.*?\bsecond\b.*?;

The above regex matches typedef struct that is not followed by another typedef struct i.e. (?!.*?typedef struct)..This is done so that multiple structs are not captured

[with groups]

(?:^|\;).*(typedef struct.*?\}.*?\bsecond\b.*?;)

Basically the above regex matches a struct that is either at the start of the file or it would match the required struct after a statement terminator..i.e ;.This is done so that other struct definitions are not included in the result..

(?:^|\;) matches the start of the string or a ; and doesnt get captured in the group

.* matches 0 to many characters greedily

(typedef struct.*?\}.*?\bsecond\b.*?;) now matches your struct

.*? matches 0 to many characters lazily

Group1 now has your required struct

Upvotes: 1

Related Questions