GREP in InDesign

Splitting Up Complex GREP Expressions

We’ve seen in some examples that GREP expressions can quickly become quite complex. One way of battling complexity is to split expressions up into separate expressions. An added benefit of splitting up expressions is that they are easier to modify. A good example of a query that benefits from splitting up is finding hyphens in ranges and replacing them with en dashes. As we will see, it’s not easy to come up with a single expression to accomplish this.

Replace Hyphens in Page Ranges with En Dashes

The ranges we’re after are ranges of numbers, both Arabic and Roman (e.g., 34-78, v-ix), ranges of numbers in parentheses (as in (23)-(27)), and certain letter ranges (a-d), which could be preceded by a number (as in 6b-d). The first type, ranges of Arabic numbers such as 23-56, can be handled with this query:

Find what:	(\d)-(\d)
Change to:	$1~=$2

Note that this query can be over-enthusiastic in that it changes hyphens in numbers which aren’t page ranges, such as such as ISBN numbers, telephone numbers, and grant numbers. The \b location marker is of no use here because hyphens are seen as word boundaries, so an expression such as \b(\d+)-(\d+)\b matches 0-596 in 978-0-596-51706-9. This can can be avoided, but we need some extra tools for that; see “Replace hyphens in page ranges—revisited” on page 47.

Hyphens in ranges of Arabic numbers in parentheses such as (12)-(14) can be captured with the following expressions:

Find what:

(?x) ([\d()]+) ...