33 lines
953 B
JavaScript
33 lines
953 B
JavaScript
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/* -*- mode: js2; js2-basic-offset: 4; indent-tabs-mode: nil -*- */
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// parse:
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// @params: caller-provided parameter object, or %null
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// @default: function-provided defaults object
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// @allowExtras: whether or not to allow properties not in @default
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//
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// Examines @params and fills in default values from @defaults for
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// any properties in @defaults that don't appear in @params. If
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// @allowExtras is not %true, it will throw an error if @params
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// contains any properties that aren't in @defaults.
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//
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// If @params is %null, this returns @defaults.
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//
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// Return value: the updated params
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function parse(params, defaults, allowExtras) {
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if (!params)
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return defaults;
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if (!allowExtras) {
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for (let prop in params) {
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if (!(prop in defaults))
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throw new Error('Unrecognized parameter "' + prop + '"');
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}
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}
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for (let prop in defaults) {
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if (!(prop in params))
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params[prop] = defaults[prop];
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}
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return params;
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}
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