our The basic building blocks of the relevance language are numbers, strings, and the expressions that combine them.
The "Q:" is the relevance query that is being run and the "A:" is the answer to your query. Queries can be complex and answers to a queries can be of any type, but more on that soon!
Strings are sets of characters (a-z,0-9,!@#$) that are surrounded by quotes. The output of the following query is the string "hello world"
- Q: "hello world"
- A: hello world
- Q: substrings separated by "-" of "an-over-hyphenated-string"
- A: an
- A: over
- A: hyphenated
- A: string
Note in the example above that four values were returned, not just one. This
output is typical of a plural inspector like
substrings. You can filter this
list with a
- Q: (substrings separated by " " of "who observed what happened, when and where?") whose (it contains "w")
- A: who
- A: what
- A: when
- A: where?
This example shows two clauses in parentheses. The first parenthetical clause
creates a list of words (substrings separated by a space). This
contains the primary keyword
it (described in greater detail below), that can
stand in for another object – in this case,
it stands in for each of the
individual words, and the expression returns just those words that contain the
letter 'w'. How many of these substrings are there?
- Q: number of (substrings separated by " " of "who observed what happened, when and where?") whose (it contains "w")
- A: 4
This expression shows how you can count the number of items returned and filtered from a plural inspector. As these examples show, you can get either singular or plural items back from a Relevance expression. What about no items at all? That's a subject for the next section.
Literal strings like this are parsed for one special character: the percent
sign. This is an escape character that encodes for other, non-printable
characters, specifically control characters and delete. When a percent sign is
found, the encoding expects the next two characters to be hex digits producing a
one-byte hex value. This hex value is then added to the internal representation
of the string, allowing you incorporate otherwise unavailable characters into a
string. Because the percent is used as the escape key, to actually get a percent
into a string you must use
%25, the hex value for percent. To convert back to
an escaped string for output, characters with a hex value less than
0x7E, or equal to
0x25 are printed as escaped characters, for example