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Add tag syntax to KQL (#137)

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Lars Willighagen 2021-09-09 19:03:07 +02:00 committed by GitHub
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QUERY-SPEC.md
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@ -24,12 +24,14 @@ lack of `*` (use `[]` instead), and the specific syntax for
## Matchers
Matchers are used to filter nodes by their various attributes (such as values,
properties, node names, etc). With the exception of `top()`, they are all used
inside a `[ ]` selector. Some matchers are unary, but most of them involve
properties, node names, etc). With the exception of `top()` and `()`, they are all
used inside a `[ ]` selector. Some matchers are unary, but most of them involve
binary operators.
* `top()`: Returns all toplevel children of the current document.
* `top() > []`: Equivalent to `top()` on its own.
* `(foo)`: Selects any element with a tag named `foo`.
* `()`: Selects any element with any tag.
* `[val()]`: Selects any element with a value.
* `[val(1)]`: Selects any element with a second value.
* `[prop(foo)]`: Selects any element with a property named `foo`.
@ -41,9 +43,10 @@ Attribute matchers support certain binary operators:
* `[prop(name) = 1]`: Selects any element with a property `name` whose value is 1.
* `[name = 1]`: Equivalent to the above.
* `[name() = "hi"]`: Selects any element whose _node name_ is "hi". Equivalent to just `hi`, but more useful when using string operators.
* `[tag() = "hi"]`: Selects any element whose tag is "hi". Equivalent to just `(hi)`, but more useful when using string operators.
* `[val() != 1]`: Selects any element whose first value exists, and is not 1.
The following operators work with any `val()`, `prop()`, or `name()` values.
The following operators work with any `val()` or `prop()` values.
If the value is not of the same type, the operator will always fail ("1" is
never coerced to 1, and there is no "universal" ordering across all types.):
@ -52,12 +55,18 @@ never coerced to 1, and there is no "universal" ordering across all types.):
* `[val() < 1]`: Selects any element whose first value is less than 1.
* `[val() <= 1]`: Selects any element whose first value is less than or equal to 1.
The following operators work only with string `val()`, `prop()`, or `name()` values. If the value is not a string, the matcher will always fail:
The following operators work only with string `val()`, `prop()`, `tag()`, or `name()` values.
If the value is not a string, the matcher will always fail:
* `[val() ^= "foo"]`: Selects any element whose first value starts with "foo".
* `[val() $= "foo"]`: Selects any element whose first value ends with "foo".
* `[val() *= "foo"]`: Selects any element whose first value contains "foo".
The following operators work only with `val()` or `prop()` values. If the value
is not one of those, the matcher will always fail:
* `[val() = (foo)]`: Selects any element whose tag is "foo".
## Map Operator
KQL implementations MAY support a "map operator", `=>`, that allows selection