Trait rsonpath::result::QueryResultBuilder

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pub trait QueryResultBuilder<'i, I: Input, R: QueryResult> {
    // Required methods
    fn new(input: &'i I) -> Self;
    fn report(
        &mut self,
        index: usize,
        hint: NodeTypeHint
    ) -> Result<(), EngineError>;
    fn finish(self) -> R;
}
Expand description

A builder for a QueryResult with access to the underlying input.

Required Methods§

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fn new(input: &'i I) -> Self

Create a new, empty builder, with access to the underlying JSON input.

Implementations should make sure that the result produced from an empty builder is the same as the empty instance of that result (defined by the Default trait). In other words, for any builder of result type R it should hold that:

ⓘ
builder.new(input).finish() == R::default()
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fn report( &mut self, index: usize, hint: NodeTypeHint ) -> Result<(), EngineError>

Report a match of the query. The index is guaranteed to be between the first character of the matched value and the previous structural character.

When the engine finds a match, it will usually occur at some structural character. It is guaranteed that index points to either:

  1. the first character of the matched value; or
  2. the character right after the colon or comma structural character directly preceding the matched value; or
  3. a whitespace character before the matched value, such that the next non-whitespace character is the first character of the matched value.

The builder should use the index and the provided hint to find the start of the actual value being reported. Note that it is always possible to do so without the hint (or, equivalently, when NodeTypeHint::Any is given), but the hint can improve performance. For example, when the hint is NodeTypeHint::Complex with the curly bracket type, the result builder can do a quick direct search for the next ‘{’ character.

{
  "match":       42
  //      ^^^^^^^^
  // any of these characters can be reported for the query $.match
}

{
  "match": [42,     30]
  //           ^^^^^^
  // any of these characters can be reported for the query $.match[1]
}
Errors

This function may access the input, which can raise an EngineError::InputError. More errors can occur if the input JSON is malformed (for example the document abruptly ends), but they are not guaranteed to be detected or reported.

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fn finish(self) -> R

Finish building the result and return it.

Implementors§