feat(ioscompanion): add USB HID keymap module

internal/driver/ioscompanion/keymap.go

@@ -0,0 +1,129 @@
+// Package ioscompanion talks to the simulator companion to drive an iOS
+// simulator. This file is pure data: it maps runes to USB HID keyboard
+// usage IDs. A later module turns these key presses into HID events.
+package ioscompanion
+
+// USB HID keyboard usage IDs.
+const (
+	usageA            = 4
+	usage1            = 30
+	usage0            = 39
+	usageReturn       = 40
+	usageTab          = 43
+	usageSpace        = 44
+	usageBackspace    = 42
+	usageMinus        = 45
+	usageEqual        = 46
+	usageLeftBracket  = 47
+	usageRightBracket = 48
+	usageBackslash    = 49
+	usageSemicolon    = 51
+	usageApostrophe   = 52
+	usageGrave        = 53
+	usageComma        = 54
+	usagePeriod       = 55
+	usageSlash        = 56
+
+	usageLeftShift = 225
+
+	// LeftGUI is the command key. VKey is the letter V. Together they form
+	// the paste chord (command+V).
+	LeftGUI = 227
+	VKey    = 25
+)
+
+// KeyPress is a single key with whether the shift modifier is held.
+type KeyPress struct {
+	Usage uint32
+	Shift bool
+}
+
+// shiftedSymbols maps a shifted-symbol rune to the unshifted key it lives on.
+var shiftedSymbols = map[rune]uint32{
+	'!': usage1,
+	'@': usage1 + 1,
+	'#': usage1 + 2,
+	'$': usage1 + 3,
+	'%': usage1 + 4,
+	'^': usage1 + 5,
+	'&': usage1 + 6,
+	'*': usage1 + 7,
+	'(': usage1 + 8,
+	')': usage0,
+	'_': usageMinus,
+	'+': usageEqual,
+	'{': usageLeftBracket,
+	'}': usageRightBracket,
+	'|': usageBackslash,
+	':': usageSemicolon,
+	'"': usageApostrophe,
+	'~': usageGrave,
+	'<': usageComma,
+	'>': usagePeriod,
+	'?': usageSlash,
+}
+
+// unshiftedSymbols maps a symbol rune typed without shift to its key.
+var unshiftedSymbols = map[rune]uint32{
+	'-':  usageMinus,
+	'=':  usageEqual,
+	'[':  usageLeftBracket,
+	']':  usageRightBracket,
+	'\\': usageBackslash,
+	';':  usageSemicolon,
+	'\'': usageApostrophe,
+	'`':  usageGrave,
+	',':  usageComma,
+	'.':  usagePeriod,
+	'/':  usageSlash,
+}
+
+// charKey returns the key press for a rune and whether the rune is mappable.
+func charKey(r rune) (KeyPress, bool) {
+	switch {
+	case r >= 'a' && r <= 'z':
+		return KeyPress{Usage: uint32(usageA + (r - 'a'))}, true
+	case r >= 'A' && r <= 'Z':
+		return KeyPress{Usage: uint32(usageA + (r - 'A')), Shift: true}, true
+	case r >= '1' && r <= '9':
+		return KeyPress{Usage: uint32(usage1 + (r - '1'))}, true
+	case r == '0':
+		return KeyPress{Usage: usage0}, true
+	case r == ' ':
+		return KeyPress{Usage: usageSpace}, true
+	case r == '\n':
+		return KeyPress{Usage: usageReturn}, true
+	case r == '\t':
+		return KeyPress{Usage: usageTab}, true
+	}
+	if usage, ok := unshiftedSymbols[r]; ok {
+		return KeyPress{Usage: usage}, true
+	}
+	if usage, ok := shiftedSymbols[r]; ok {
+		return KeyPress{Usage: usage, Shift: true}, true
+	}
+	return KeyPress{}, false
+}
+
+// typeString returns the ordered key presses for every mappable rune in s.
+// Unmappable runes are collected in order in skipped.
+func typeString(s string) (presses []KeyPress, skipped []rune) {
+	for _, r := range s {
+		press, ok := charKey(r)
+		if !ok {
+			skipped = append(skipped, r)
+			continue
+		}
+		presses = append(presses, press)
+	}
+	return presses, skipped
+}
+
+// backspaces returns n backspace key presses.
+func backspaces(n int) []KeyPress {
+	presses := make([]KeyPress, 0, n)
+	for i := 0; i < n; i++ {
+		presses = append(presses, KeyPress{Usage: usageBackspace})
+	}
+	return presses
+}