index()
Summary
The index() statement maps a character from an input store to an
output store.
Syntax
any(inputStore) > index(outputStore,offset)Parameters
outputStore
: The store from which the output character is selected. This store
should be the same length as the inputStore.
offset
: The character offset of the any() statement in the left hand side
of the rule to pair with, starting at 1. The index increments for
each character or statement found, with one caveat: outs()
statements are expanded prior to calculating the offset. Note that
unlike the context() statement, the offset calculation
does include if() statements.
Description
The index() statement works together with any() to map an
array of characters in inputStore to a corresponding array in
outputStore. index() can be used in the context and output
sections of a rule. If used in the context section, the offset
parameter must be less than the offset of the index() statement in
the context.
The stores can include deadkey() statements, outs() statements and
virtual keys; the outs() statement is expanded prior to the
calculation of offsets within the input and output stores. When a store
contains virtual keys, it can be used only with the any() statement in
the key part of the rule.
Conceptually, the index() and any() pairing can be expanded into
multiple rules, one for each pair of characters. If expanded, this would
grow the rule set exponentially when multiple pairs of index() and
any() are used in the same rule.
Examples
Example: Using index()
This example maps a vowel, followed by a diacritic key, to the same vowel, and a corresponding combining diacritic mark.
store(vowel) "aeiou"
store(diacritickey) "`'^"
store(diacriticCombining) U+0300 U+0301 U+0302
any(vowel) + any(diacritickey) > index(vowel,1) index(diacriticCombining,2)
c this could also be expressed with the context statement:
any(vowel) + any(diacritickey) > context index(diacriticCombining,2)This example does the same as the previous, except it reverses the input
order: a diacritic mark first, then a vowel, and uses the index()
statement to swap the results in the output.
store(vowel) "aeiou"
store(diacritickey) "`'^"
store(diacriticCombining) U+0300 U+0301 U+0302
any(diacritickey) + any(vowel) > index(vowel,2) index(diacriticCombining,1)The following example shows how the index statement can be used in the
left hand side of a rule. If a repeating vowel is found, then this rule
puts a circumflex on top of both vowels when
store(vowel) "aeiou"
store(vowelcirc) "âêîôû"
any(vowel) index(vowel,1) + "^" > index(vowelcirc,1) index(vowelcirc,2)Platforms
The index() statement can be used in keyboards on all platforms.
| Windows | macOS | Linux | Desktop web | Mobile web | iOS | Android |
|---|---|---|---|---|---|---|
| ✔ | ✔ | ✔ | ✔ | ✔ | ✔ | ✔ |
Note
For mobile and mobile web, the statement is only accessible as the output section of the rule.
Version history
The index() statement was introduced in Keyman 3.0. As of version
6.0, it can also be used in the left-hand side of a rule.
