Trait mz_repr::explain::Explain

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pub trait Explain<'a>: 'a {
    type Context;
    type Text: DisplayText;
    type Json: DisplayJson;
    type Dot: DisplayDot;

    // Provided methods
    fn explain(
        &'a mut self,
        format: &'a ExplainFormat,
        context: &'a Self::Context
    ) -> Result<String, ExplainError> { ... }
    fn explain_text(
        &'a mut self,
        context: &'a Self::Context
    ) -> Result<Self::Text, ExplainError> { ... }
    fn explain_json(
        &'a mut self,
        context: &'a Self::Context
    ) -> Result<Self::Json, ExplainError> { ... }
    fn explain_dot(
        &'a mut self,
        context: &'a Self::Context
    ) -> Result<Self::Dot, ExplainError> { ... }
}
Expand description

A trait that provides a unified interface for objects that can be explained.

All possible subjects of the various forms of an EXPLAIN SQL statement should implement this trait.

Required Associated Types§

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type Context

The type of the immutable context in which the explanation will be rendered.

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type Text: DisplayText

The explanation type produced by a successful Explain::explain_text call.

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type Json: DisplayJson

The explanation type produced by a successful Explain::explain_json call.

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type Dot: DisplayDot

The explanation type produced by a successful Explain::explain_json call.

Provided Methods§

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fn explain( &'a mut self, format: &'a ExplainFormat, context: &'a Self::Context ) -> Result<String, ExplainError>

Explain an instance of Self within the given Explain::Context.

Implementors should never have the need to not rely on this default implementation.

§Errors

If the given format is not supported, the implementation should return an ExplainError::UnsupportedFormat.

If an ExplainConfig parameter cannot be honored, the implementation should silently ignore this parameter and proceed without returning a Result::Err.

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fn explain_text( &'a mut self, context: &'a Self::Context ) -> Result<Self::Text, ExplainError>

Construct a Result::Ok of the Explain::Text format from the config and the context.

§Errors

If the ExplainFormat::Text is not supported, the implementation should return an ExplainError::UnsupportedFormat.

If an ExplainConfig parameter cannot be honored, the implementation should silently ignore this paramter and proceed without returning a Result::Err.

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fn explain_json( &'a mut self, context: &'a Self::Context ) -> Result<Self::Json, ExplainError>

Construct a Result::Ok of the Explain::Json format from the config and the context.

§Errors

If the ExplainFormat::Text is not supported, the implementation should return an ExplainError::UnsupportedFormat.

If an ExplainConfig parameter cannot be honored, the implementation should silently ignore this paramter and proceed without returning a Result::Err.

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fn explain_dot( &'a mut self, context: &'a Self::Context ) -> Result<Self::Dot, ExplainError>

Construct a Result::Ok of the Explain::Dot format from the config and the context.

§Errors

If the ExplainFormat::Dot is not supported, the implementation should return an ExplainError::UnsupportedFormat.

If an ExplainConfig parameter cannot be honored, the implementation should silently ignore this paramter and proceed without returning a Result::Err.

Implementors§