View Source EEx (EEx v1.17.2)
EEx stands for Embedded Elixir.
Embedded Elixir allows you to embed Elixir code inside a string in a robust way.
iex> EEx.eval_string("foo <%= bar %>", bar: "baz")
"foo baz"
This module provides three main APIs for you to use:
Evaluate a string (
eval_string/3
) or a file (eval_file/3
) directly. This is the simplest API to use but also the slowest, since the code is evaluated at runtime and not precompiled.Define a function from a string (
function_from_string/5
) or a file (function_from_file/5
). This allows you to embed the template as a function inside a module which will then be compiled. This is the preferred API if you have access to the template at compilation time.Compile a string (
compile_string/2
) or a file (compile_file/2
) into Elixir syntax tree. This is the API used by both functions above and is available to you if you want to provide your own ways of handling the compiled template.
The APIs above support several options, documented below. You may also pass an engine which customizes how the EEx code is compiled.
Options
All functions in this module, unless otherwise noted, accept EEx-related options. They are:
:file
- the file to be used in the template. Defaults to the given file the template is read from or to"nofile"
when compiling from a string.:line
- the line to be used as the template start. Defaults to1
.:indentation
- (since v1.11.0) an integer added to the column after every new line. Defaults to0
.:engine
- the EEx engine to be used for compilation. Defaults toEEx.SmartEngine
.:trim
- iftrue
, trims whitespace left and right of quotation as long as at least one newline is present. All subsequent newlines and spaces are removed but one newline is retained. Defaults tofalse
.:parser_options
- (since: 1.13.0) allow customizing the parsed code that is generated. SeeCode.string_to_quoted/2
for available options. Note that the options:file
,:line
and:column
are ignored if passed in. Defaults toCode.get_compiler_option(:parser_options)
(which defaults to[]
if not set).
Tags
EEx supports multiple tags, declared below:
<% Elixir expression: executes code but discards output %>
<%= Elixir expression: executes code and prints result %>
<%% EEx quotation: returns the contents inside the tag as is %>
<%!-- Comments: they are discarded from source --%>
EEx supports additional tags, that may be used by some engines, but they do not have a meaning by default:
<%| ... %>
<%/ ... %>
Engine
EEx has the concept of engines which allows you to modify or transform the code extracted from the given string or file.
By default, EEx
uses the EEx.SmartEngine
that provides some
conveniences on top of the simple EEx.Engine
.
EEx.SmartEngine
The smart engine uses EEx default rules and adds the @
construct
for reading template assigns:
iex> EEx.eval_string("<%= @foo %>", assigns: [foo: 1])
"1"
In other words, <%= @foo %>
translates to:
<%= {:ok, v} = Access.fetch(assigns, :foo); v %>
The assigns
extension is useful when the number of variables
required by the template is not specified at compilation time.
Summary
Functions
Gets a filename
and generates a quoted expression
that can be evaluated by Elixir or compiled to a function.
Gets a string source
and generates a quoted expression
that can be evaluated by Elixir or compiled to a function.
Gets a filename
and evaluate the values using the bindings
.
Gets a string source
and evaluate the values using the bindings
.
Generates a function definition from the file contents.
Generates a function definition from the given string.
Tokenize the given contents according to the given options.
Types
@type column() :: non_neg_integer()
@type line() :: non_neg_integer()
@type marker() :: ~c"=" | ~c"/" | ~c"|" | []
Functions
Gets a filename
and generates a quoted expression
that can be evaluated by Elixir or compiled to a function.
This is useful if you want to compile a EEx template into code and inject that code somewhere or evaluate it at runtime.
The generated quoted code will use variables defined in the template that
will be taken from the context where the code is evaluated. If you
have a template such as <%= a + b %>
, then the returned quoted code
will use the a
and b
variables in the context where it's evaluated. See
examples below.
The supported options
are described in the module docs.
Examples
# sample.eex
<%= a + b %>
# In code:
quoted = EEx.compile_file("sample.eex")
{result, _bindings} = Code.eval_quoted(quoted, a: 1, b: 2)
result
#=> "3"
Gets a string source
and generates a quoted expression
that can be evaluated by Elixir or compiled to a function.
This is useful if you want to compile a EEx template into code and inject that code somewhere or evaluate it at runtime.
The generated quoted code will use variables defined in the template that
will be taken from the context where the code is evaluated. If you
have a template such as <%= a + b %>
, then the returned quoted code
will use the a
and b
variables in the context where it's evaluated. See
examples below.
The supported options
are described in the module docs.
Examples
iex> quoted = EEx.compile_string("<%= a + b %>")
iex> {result, _bindings} = Code.eval_quoted(quoted, a: 1, b: 2)
iex> result
"3"
Gets a filename
and evaluate the values using the bindings
.
The supported options
are described in the module docs.
Examples
# sample.eex
foo <%= bar %>
# IEx
EEx.eval_file("sample.eex", bar: "baz")
#=> "foo baz"
Gets a string source
and evaluate the values using the bindings
.
The supported options
are described in the module docs.
Examples
iex> EEx.eval_string("foo <%= bar %>", bar: "baz")
"foo baz"
function_from_file(kind, name, file, args \\ [], options \\ [])
View Source (macro)Generates a function definition from the file contents.
The first argument is the kind of the generated function (:def
or :defp
).
The name
argument is the name that the generated function will have.
file
is the path to the EEx template file. args
is a list of arguments
that the generated function will accept. They will be available inside the EEx
template.
This function is useful in case you have templates but you want to precompile inside a module for speed.
The supported options
are described in the module docs.
Examples
# sample.eex
<%= a + b %>
# sample.ex
defmodule Sample do
require EEx
EEx.function_from_file(:def, :sample, "sample.eex", [:a, :b])
end
# iex
Sample.sample(1, 2)
#=> "3"
function_from_string(kind, name, template, args \\ [], options \\ [])
View Source (macro)Generates a function definition from the given string.
The first argument is the kind of the generated function (:def
or :defp
).
The name
argument is the name that the generated function will have.
template
is the string containing the EEx template. args
is a list of arguments
that the generated function will accept. They will be available inside the EEx
template.
The supported options
are described in the module docs.
Examples
iex> defmodule Sample do
...> require EEx
...> EEx.function_from_string(:def, :sample, "<%= a + b %>", [:a, :b])
...> end
iex> Sample.sample(1, 2)
"3"
@spec tokenize([char()] | String.t(), opts :: keyword()) :: {:ok, [token()]} | {:error, String.t(), metadata()}
Tokenize the given contents according to the given options.
Options
:line
- An integer to start as line. Default is 1.:column
- An integer to start as column. Default is 1.:indentation
- An integer that indicates the indentation. Default is 0.:trim
- Tells the tokenizer to either trim the content or not. Default is false.:file
- Can be either a file or a string "nofile".
Examples
iex> EEx.tokenize(~c"foo", line: 1, column: 1)
{:ok, [{:text, ~c"foo", %{column: 1, line: 1}}, {:eof, %{column: 4, line: 1}}]}
Result
It returns {:ok, [token]}
where a token is one of:
{:text, content, %{column: column, line: line}}
{:expr, marker, content, %{column: column, line: line}}
{:start_expr, marker, content, %{column: column, line: line}}
{:middle_expr, marker, content, %{column: column, line: line}}
{:end_expr, marker, content, %{column: column, line: line}}
{:eof, %{column: column, line: line}}
Or {:error, message, %{column: column, line: line}}
in case of errors.
Note new tokens may be added in the future.