EEx

v1.8.1

EEx.Engine behaviour View Source

Basic EEx engine that ships with Elixir.

An engine needs to implement all callbacks below.

An engine may also use EEx.Engine to get the default behaviour but this is not advised. In such cases, if any of the callbacks are overridden, they must call super() to delegate to the underlying EEx.Engine.

Link to this section Summary

Types

state()

Functions

handle_assign(arg)

Handles assigns in quoted expressions

Callbacks

handle_begin(state)

Invoked at the beginning of every nesting

handle_body(state)

Called at the end of every template

handle_end(state)

Invokes at the end of a nesting

handle_expr(state, marker, expr)

Called for the dynamic/code parts of a template

handle_text(state, text)

Called for the text/static parts of a template

init(opts)

Called at the beginning of every template

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Link to this section Functions

Link to this function

handle_assign(arg) View Source 
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

Link to this section Callbacks

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handle_begin(state) View Source 
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.

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

Called at the end of every template.

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

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

Invokes at the end of a nesting.

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

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handle_expr(state, marker, expr) View Source 
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.

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handle_text(state, text) View Source 
handle_text(state(), text :: String.t()) :: state()

Called for the text/static parts of a template.

It must return the updated state.

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init(opts) View Source 
init(opts :: keyword()) :: state()

Called at the beginning of every template.

It must return the initial state.