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Read-only signals whose value is a function of other signals, recomputed automatically at sync time. Supports String, Int, Bool, and Text methods. Components store computed signals on the parent page context like regular signals.
56 lines
1.1 KiB
Go
56 lines
1.1 KiB
Go
package via
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import (
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"fmt"
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"strconv"
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"strings"
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"github.com/ryanhamamura/via/h"
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)
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// computedSignal is a read-only signal whose value is derived from other signals.
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// It recomputes on every read and is included in patches only when the value changes.
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type computedSignal struct {
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id string
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compute func() string
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lastVal string
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changed bool
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}
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func (s *computedSignal) ID() string {
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return s.id
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}
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func (s *computedSignal) String() string {
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return s.compute()
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}
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func (s *computedSignal) Int() int {
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if n, err := strconv.Atoi(s.String()); err == nil {
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return n
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}
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return 0
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}
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func (s *computedSignal) Bool() bool {
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val := strings.ToLower(s.String())
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return val == "true" || val == "1" || val == "yes" || val == "on"
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}
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func (s *computedSignal) Text() h.H {
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return h.Span(h.Data("text", "$"+s.id))
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}
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// recompute calls the compute function and sets changed if the value differs from lastVal.
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func (s *computedSignal) recompute() {
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val := s.compute()
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if val != s.lastVal {
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s.lastVal = val
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s.changed = true
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}
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}
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func (s *computedSignal) patchValue() string {
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return fmt.Sprintf("%v", s.lastVal)
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}
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