EEx.Engine behaviour (EEx v1.12.3) View Source

Basic EEx engine that ships with Elixir.

An engine needs to implement all callbacks below.

This module also ships with a default engine implementation you can delegate to. See EEx.SmartEngine as an example.

Link to this section Summary

Callbacks

Invoked at the beginning of every nesting.

Called at the end of every template.

Invokes at the end of a nesting.

Called for the dynamic/code parts of a template.

Called for the text/static parts of a template.

Called at the beginning of every template.

Functions

Handles assigns in quoted expressions.

Default implementation for handle_begin/1.

Default implementation for handle_body/1.

Default implementation for handle_end/1.

Default implementation for handle_expr/3.

Default implementation for handle_text/3.

Default implementation for init/1.

Link to this section Types

Specs

state() :: term()

Link to this section Callbacks

Specs

handle_begin(state()) :: state()

Invoked at the beginning of every nesting.

It must return a new state that is used only inside the nesting. Once the nesting terminates, the current state is resumed.

Specs

handle_body(state()) :: Macro.t()

Called at the end of every template.

It must return Elixir's quoted expressions for the template.

Specs

handle_end(state()) :: Macro.t()

Invokes at the end of a nesting.

It must return Elixir's quoted expressions for the nesting.

Link to this callback

handle_expr(state, marker, expr)

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Specs

handle_expr(state(), marker :: String.t(), expr :: Macro.t()) :: state()

Called for the dynamic/code parts of a template.

The marker is what follows exactly after <%. For example, <% foo %> has an empty marker, but <%= foo %> has "=" as marker. The allowed markers so far are:

  • ""
  • "="
  • "/"
  • "|"

Markers "/" and "|" are only for use in custom EEx engines and are not implemented by default. Using them without an appropriate implementation raises EEx.SyntaxError.

It must return the updated state.

Link to this callback

handle_text(state, list, text)

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Specs

handle_text(
  state(),
  [line: pos_integer(), column: pos_integer()],
  text :: String.t()
) :: state()

Called for the text/static parts of a template.

It must return the updated state.

Specs

init(opts :: keyword()) :: state()

Called at the beginning of every template.

It must return the initial state.

Link to this section Functions

Specs

handle_assign(Macro.t()) :: Macro.t()

Handles assigns in quoted expressions.

A warning will be printed on missing assigns. Future versions will raise.

This can be added to any custom engine by invoking handle_assign/1 with Macro.prewalk/2:

def handle_expr(state, token, expr) do
  expr = Macro.prewalk(expr, &EEx.Engine.handle_assign/1)
  super(state, token, expr)
end

Default implementation for handle_begin/1.

Default implementation for handle_body/1.

Default implementation for handle_end/1.

Link to this function

handle_expr(state, marker, ast)

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Default implementation for handle_expr/3.

Link to this function

handle_text(state, meta, text)

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Default implementation for handle_text/3.

Default implementation for init/1.