Resolvable boolean expressions #164
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ilyapuchka
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removed static boolean expressions added test for rendering template with boolean expression
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CHANGELOG.md
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| [#178](https://github.com/stencilproject/Stencil/pull/178) | ||
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| - Now boolean expressions results can be rendered, i.e `{{ name == "John" }}` will render `true` or `false` depending on the evaluation result |
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Forgot the . and 2 spaces. Also remove the empty line above.
| /// Resolves a variable in the given context as boolean | ||
| func resolve(context: Context, variable: Resolvable) throws -> Bool { | ||
| func evaluate(context: Context) throws -> Bool { |
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Weird, I think I've seen this change a few times in other PRs? 😕😆
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maybe, some features required similar changes
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Before I forget: This PR should document the changes in the |
| let expression = try! parseExpression(components: ["lhs", "or", "rhs"], tokenParser: parser) | ||
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| let components = ["lhs", "or", "rhs"] | ||
| @@ -95,11 +100,17 @@ func testExpressions() { | |||
| $0.it("returns truthy for positive expressions") { | |||
| let expression = NotExpression(expression: StaticExpression(value: true)) | |||
| try expect(expression.evaluate(context: Context())).to.beFalse() | |||
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| try expect(Template(templateString: "{% if true %}true{% else %}false{% endif %}").render(Context())) == "true" | |||
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Since this is the unit tests for expression, I do not want to test other units in this file. This is further becoming an integration test when we are creating a template and testing other functionality such as the `if statements.
| @@ -136,163 +147,172 @@ func testExpressions() { | |||
| } | |||
| } | |||
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| func expectExpression(with components: [String], context: [String: Any], toBe expected: Bool) throws { | |||
| let expression = try parseExpression(components: components, tokenParser: parser) | |||
| try expect(expression.evaluate(context: Context(dictionary: context))) == expected | |||
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This will cause the source maps for the thrown error when the tests fail to be raised from here making test failures harder to pinpoint. To solve this we can grab the file and line number from the expectExpression invocation and pass it to expect:
func expectExpression(..., file: String = #file, line: Int = #line, function: String = #function) {
...
try expect(..., file: file, line: line, function: function) == expected
}
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@ilyapuchka why close this? The docs are there, it should be GTM. |
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there were conflicts and tests started to fail for some reason after I merged, I'll need to to investigate that but I also don't feel like this is a top priority considering other open PRs |
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Which tests? CI succeeds for the latest commit in this PR. |
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Only because I didn't push 😉 |
This PR adds ability to resolve boolean expressions the same way as variables like
{{ this == that }}This have a potential to simplify templates when there is a need to evaluate boolean expression and output its result, true or false, in a template, i.e. when generating html to enable or disable html elements. Instead of
{% if this == that %}true{% else %}false{% endif %}it will be possible to write just{{ this == that }}Also this PR adds support for parsing static boolean expressions, i.e. if
{% if true %}. There was implementation for such expression and tests for it, but it was never actually parsed. It may not be very important, but can be helpful during template development.