Chapter 3. Compiler and Tools

The pcre_exec() function now checks for out-of-range starting offset values and reports PCRE_ERROR_BADOFFSET errors instead of reporting PCRE_ERROR_NOMATCH errors or looping infinitely.

If the pcre_exec() function is called to perform a UTF-8 match on an invalid UTF-8 subject string and the ovector array argument is large enough, the offset of the first subject string in the invalid UTF-8 byte, as well as the detailed reason code, are returned in the ovector array element. In addition, the pcretest utility can now be used to display these details. Note that with this update, the pcre_compile() function reports first invalid UTF-8 byte instead of the last byte. Also note that the signature of the pcre_valid_utf8() function, which is not intended for public use, has been changed. Finally, note that the pcretest utility now appends human-readable error messages to error codes.

The Vim text editor now supports persistent reverting of changes that can by enabled by setting the undofile option. By default, when unloading a buffer, Vim destroys the tree of changes created for that buffer. However, when enabling persistent reverting of changes, Vim automatically saves the history of changes and restores it after reopening the buffer again.

This update introduces a new regular expressions engine. The previous engine used the backtracking algorithm; the pattern was matched against the text in one way and when this attempt failed, the pattern was matched in another way. This engine worked correctly for simple patterns, however, it took significantly longer to match a complex pattern in a longer text. The new engine uses the state machine logic; it tries all possible alternatives at the current character and stores the possible states of the pattern. Although, this process is little bit slower for simple patterns, matching complex patterns against longer texts is faster. Most notably, syntax highlighting for JavaScript and XML files with long lines was improved by this change.