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91 lines
2.6 KiB
Markdown
91 lines
2.6 KiB
Markdown
## Declarations
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## Table of Contents
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* [Syntax](#syntax)
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* [Definitions](#definitions)
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* [Current Declaration Name](#current-declaration-name)
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* [Semantics](#semantics)
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## Syntax
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<x><pre>
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**Declaration** ::= StandardDeclaration | CustomDeclaration
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**StandardDeclaration** ::= [InterpolatedIdentifier]¹ ':' (Value | Value? '{' Statements '}')
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**CustomDeclaration** ::= [InterpolatedIdentifier]² ':' InterpolatedDeclarationValue
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</pre></x>
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1. This may not begin with "--".
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2. This *must* begin with "--".
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[InterpolatedIdentifier]: syntax.md#interpolatedidentifier
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## Definitions
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### Current Declaration Name
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The *current declaration name* is the innermost value declared as such when
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[executing a declaration].
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[executing a declaration]: #semantics
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### Semantics
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To execute a declaration `declaration`:
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* Let `parent-name` be the [current declaration name], if one exists.
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[current declaration name]: #current-declaration-name
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* If `name` is set and `declaration` is a [`CustomDeclaration`], throw an error.
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[`CustomDeclaration`]: #syntax
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* Let `name` be the result of evaluating the all interpolation in
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`declaration`'s name.
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* If `parent-name` exists, set `name` to `parent-name + "-" + name`.
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* Declare `name` as the [current declaration name] for the duration of executing
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`declaration`.
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* If `declaration` has a `Value`:
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* Let `value` be the result of evaluating that `Value`.
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* Otherwise, if `declaration` is a `CustomDeclaration`:
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* Let `value` be an unquoted string whose value is the result of evaluating
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`declaration`'s `InterpolatedDeclarationValue`.
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* If `value` is empty, throw an error.
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> Note that `value` being only whitespace is allowed, including `--foo: ;`.
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* Let `parent` be the [current style rule], [keyframe block], or at-rule; or
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the innermost if multiple exist.
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[current style rule]: style-rules.md#current-style-rule
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[keyframe block]: style-rules.md#current-style-rule
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> Parsing guarantees that a declaration will have at least one parent.
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* If `value` is set, and it's neither null nor an empty unquoted string:
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* Let `css` be a CSS declaration with name `name` and value `value`.
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* Append `css` to `parent`.
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* If `parent` isn't the last statement in its parent:
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* Let `copy` by a copy of `parent` without any children.
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* Append `copy` to `parent`'s parent.
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* Set the [current style rule], [keyframe block], or at-rule (according to
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`copy`'s type) to `copy`, for the remaining duration of its previous value.
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* Set `parent` to `copy`.
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* Evaluate each child in `declaration`'s `Statements` if it exists.
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