Step 4: The Keyboard Body

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The body of the keyboard is the most important part: it determines the behaviour of the keyboard. The body consists of groups, which in turn contain one or more rules which define the responses of the keyboard to certain keystrokes.

Groups

There are two types of groups:

• groups that process the keys pressed and the context.
• groups that process only the context.

For simple keyboards, the latter type of group will not be required. A group begins with a group statement, and ends either at the start of another group, or at the end of the keyboard file.

We will only use one group in the Quick French keyboard, called Main. We mark the start of it with the group statement below. Add this line to the keyboard if it's not already there.

group(Main) using keys          

The using keys clause tells Keyman that this group will process keystrokes.

Basic Rules

A rule tells Keyman the output to produce for a certain input. A rule consists of three parts: the context, the key, and the output.

• The context specifies the conditions under which a rule will act. If what is shown in the document to the left of the cursor matches the context of a rule, the rule will be processed.
• The key specifies which keystroke the rule will act upon.
• The output determines the characters that are produced by a rule. The output replaces the matched context in the document.

Simple rules

The simplest rules in Keyman consist of just a key and output, as below. (The examples in this section are just for illustration, and do not form part of the Quick French keyboard).

+ "a" > "ä"

In this rule, the key is a, and the output is "ä". A simple rule begins with a plus sign, followed by the key, a greater-than symbol (suggesting "becomes"), and finally the output. As you might guess, this rule will change a lowercase a key typed by the user into ä.

The key and output can be written as a character in single or double quotes (as above), or as its Unicode character code, or using a named constant. The rule above could have also been written any of the following ways, among others:

+ 'a' > 'ä'

+ U+0061 > U+00E4

store(ADIERESIS) 'ä'
+ 'a' > $ADIERESIS

You can also write the key in one form and the context in another.

Rules with longer output

The output of a rule is not limited to a single character. You could, for example, write a rule such as the following:

+ "f" > "ph"

This would change any f keys typed into ph. If the output of a rule consists of more than one character, you can write the characters in different ways if necessary, with a space separating each part. You can specify multiple characters in quotes, but if you use the Unicode codes to write the characters, you must separate each with a space:

+ "f" > U+0070 U+0068

+ "f" > U+0070 "h"

These rules are functionally identical to the one further above.

• Continue with Step 5: Rules with Context
• Back to Step 3: The Keyboard Header