Scanners are generated from “lexer types” or “skeletons”. ITPilot includes some options for the lexer type. Any option is valid for most applications, but there are some situations in which a specific one is preferred. This section describes the available options and provides some examples. The options are:
Replace tags inside extracted values with spaces. When a DEXTL specification that makes use of a scanner generated from this lexer type, extracts any data element such that this piece of information contains an HTML element (or several adjacent HTML elements), this element (or group of adjacent elements) will be replaced by a blank space.
Remove tags inside extracted values. When a DEXTL specification that makes use of a scanner generated from this lexer type, extracts any data element which contains an HTML element, this element will be removed.
The following example illustrates the difference between the two first options. Let us suppose that an Extractor for an electronic bookstore has been created. Among other fields, the extractor obtains the list of authors of every book. In the HTML code of the source, authors are shown with just a <BR> tag delimitation. For instance:
Jones, Peter <BR> Smith, John
If the option Replace tags inside extracted values with spaces is used, the extraction process will substitute the <BR> tags by blank spaces, and the retrieved value will be ‘Jones, Peter Smith, John’. In case the option Remove tags inside extracted values, the retrieved value will be ‘Jones, PeterSmith, John’.
The following example shows when the option Remove tags inside extracted values is useful. Let us suppose that an electronic bookstore allows searching by specifying the first letters of any word contained in any book’s title. The results of that search show the searched key in bold letters. For instance, the result of a search by ‘enterpr’ might contain HTML fragments such as the following:
Advice for <B>Enterpr</B>ise leaders
<B>Enterpr</B>ise Information Systems
In this case, if an Extractor based on the lexer type Remove tags inside extracted values is created, it would return the values Advice for Enterprise leaders and ‘Enterprise Information Systems’, while an Extractor based on the option Replace tags inside extracted values with spaces would return the values ‘Advice for Enterpr ise leaders’ and ‘Enterpr ise Information Systems’ (notice the blank spaces).