Step 6: Stores, any(), and index()
When we have many similar rules, as in the last example on the previous
page, we can group them together into one rule by using stores. A store
is a set of characters that are grouped under a single name. Stores are
used in rules with the any() and
index() statements. We create a
store with a store() statement:
store(vowels) "aeiou"This creates a store called vowels, which contains the five lowercase
vowels. Note that we could also have written the content of the store
using ANSI or Unicode character codes, in the same way as the output.
The any() statement is used to match a character from a specific
store. For example, the following rule will replace any vowel with a
period, when used with the store above:
+ any(vowels) > "."The any() statement can be used in the context or in the key part of a
rule. It cannot be used in the output.
The second statement that is used with stores is the index()
statement. It is usually used in the output of a rule, and will output
the character from a particular store at the same position as the
character matched by a specified any() statement. This is best shown
with an example; this rule will convert all input to uppercase:
store(lowercase) "abcdefghijklmnopqrstuvwxyz"
store(uppercase) "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
+ any(lowercase) > index(uppercase,1)When a letter, such as j is typed, the any()
statement finds its position in the lowercase store; the index()
statement then gets this index from the any() statement, and outputs
the character at the same position in the uppercase store, in this
case J.
The index() statement has two parts: the store from which it takes the
output character, and the offset of the any() statement that it gets
the character position from. This offset is found by counting the
characters and statements in the context and key parts of the rule up to
the any() statement. Again, a few examples may help to illustrate
this:
"a" + any(somestore) > index(otherstore,2) c The 'any' statement
c is character #2
"ab" any(somestore) + "c" > index(otherstore,3) c The 'any' statement
c is character #3
c Here the 'index' statement references the second 'any' statement used,
c which is character #4
U+0041 any(somestore) "B" + any(otherstore) > index(thirdstore,4)
c You can have multiple 'index' statements in the output, which can
c reference the same or different 'any's
any(store1) + any(store2) > index(store1,2) index(store2,1) index(store3,2)Using stores in the Quick French keyboard
We can now reduce the number of rules needed for the Quick French
keyboard by using stores. We will make five stores: one for the
unaccented vowels, and one each for vowels with acute accents, grave
accents, circumflexes, and diereses. For clarity, the group()
statement is repeated below:
group(Main) using keys
store( plainvowels ) 'a' 'e' 'i' 'o' 'u' 'A' 'E' 'I' 'O' 'U'
store( acutevowels ) U+00E1 U+00E9 U+00ED U+00F3 U+00FA U+00C1 U+00C9 U+00CD U+00D3 U+00DA
store( gravevowels ) U+00E0 U+00E8 U+00EC U+00F2 U+00F9 U+00C0 U+00C8 U+00CC U+00D2 U+00D9
store( circumvowels ) U+00E2 U+00EA U+00EE U+00F4 U+00FB U+00C2 U+00CA U+00CE U+00D4 U+00DB
store( dresisvowels ) U+00E4 U+00EB U+00EF U+00F6 U+00FC U+00C4 U+00CB U+00CF U+00D6 U+00DC
"'" + any( plainvowels ) > index( acutevowels, 2 )
"`" + any( plainvowels ) > index( gravevowels, 2 )
"^" + any( plainvowels ) > index( circumvowels, 2 )
'"' + any( plainvowels ) > index( dresisvowels, 2 )This is far clearer than the long list of rules that we used earlier. Obviously we should add one or two more ordinary rules to produce upper- and lower-case ç, ý, and also the angled quotes « and ». Then we will have almost finished the keyboard:
"'" + "y" > U+00FD c Acute-accented Y
"'" + "Y" > U+00DD
"'" + "c" > U+00E7 c C-cedilla
"'" + "C" > U+00C7
"<" + "<" > U+00AB c Angled quotes
">" + ">" > U+00BBAll we need to do now is to test the keyboard.
