50 lines
1.2 KiB
JavaScript
50 lines
1.2 KiB
JavaScript
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// Implementation of the Event Handler With State Pattern - JS Style
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/// Initialize user-provided state.
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fn init() {
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// Can detect system-provided default states!
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// Add 'bool_state' as new state variable if one does not exist
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if !("bool_state" in this) {
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this.bool_state = false;
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}
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// Add 'value' as new state variable (overwrites any existing)
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this.value = 0;
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// Can also add OOP-style functions!
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this.log = |x| print(`State = ${this.value}, data = ${x}`);
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}
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/// 'start' event handler
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fn start(data) {
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if this.bool_state {
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throw "Already started!";
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}
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if this.value <= 0 {
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throw "Conditions not yet ready to start!";
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}
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this.bool_state = true;
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this.value += parse_int(data);
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// Constant 'MY_CONSTANT' in custom scope is also visible!
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print(`MY_CONSTANT = ${MY_CONSTANT}`);
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}
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/// 'end' event handler
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fn end(data) {
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if !this.bool_state {
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throw "Not yet started!";
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}
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if this.value > 0 {
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throw "Conditions not yet ready to end!";
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}
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this.bool_state = false;
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this.value = parse_int(data);
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}
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/// 'update' event handler
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fn update(data) {
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let data = parse_int(data);
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this.value += data;
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this.log(data);
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}
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