# `Cldr.Number.Parser`
[🔗](https://github.com/elixir-cldr/cldr_numbers/blob/v2.38.1/lib/cldr/number/parse.ex#L1)

Functions for parsing numbers and currencies from
a string.

# `per`

```elixir
@type per() :: :percent | :permille
```

# `find_and_replace`
*since 2.22.0* 

```elixir
@spec find_and_replace(%{required(binary()) => term()}, binary(), float() | nil) ::
  {:ok, list()} | {:error, {module(), binary()}}
```

Find a substring at the beginning and/or end of a
string, and replace it.

Ignore any whitespace found at the start or end of the
string when looking for a match. A match is considered
only if there is no alphabetic character adjacent to
the match.

When multiple matches are found, the longest match
is replaced.

## Arguments

* `string_map` is a map where the keys are the strings
  to be matched and the values are the replacement.

* `string` is the string in which the find and replace
  operation takes place.

* `fuzzy` is floating point number between 0.0 and 1.0
  that is used to implement a fuzzy match using
  `String.jaro_distance/2`. The default is `nil` which
  means the match is exact at the beginning and/or the
  end of the `string`.

## Returns

* `{:ok, list}` where list is `string` broken into the
  replacement(s) and the remainder after find and replace. Or

* `{:error, {exception, reason}}` will be returned if
  the `fuzzy` parameter is invalid or if no search was found
  and no replacement made. In the later case, `exception`
  will be `Cldr.Number.ParseError`.

## Examples

    iex> Cldr.Number.Parser.find_and_replace(%{"this" => "that"}, "This is a string")
    {:ok, ["that", " is a string"]}

    iex> Cldr.Number.Parser.find_and_replace(%{"string" => "term"}, "This is a string")
    {:ok, ["This is a ", "term"]}

    iex> Cldr.Number.Parser.find_and_replace(%{"string" => "term", "this" => "that"}, "This is a string")
    {:ok, ["that", " is a ", "term"]}

    iex> Cldr.Number.Parser.find_and_replace(%{"unknown" => "term"}, "This is a string")
    {:error, {Cldr.Number.ParseError, "No match was found"}}

# `parse`

```elixir
@spec parse(String.t(), Keyword.t()) ::
  {:ok, integer() | float() | Decimal.t()} | {:error, {module(), String.t()}}
```

Parse a string in a locale-aware manner and return
a number.

## Arguments

* `string` is any `t:String`

* `options` is a keyword list of options

## Options

* `:number` is one of `:integer`, `:float`,
  `:decimal` or `nil`. The default is `nil`
  meaning that the type auto-detected as either
  an `integer` or a `float`.

* `:backend` is any module that includes `use Cldr`
  and is therefore a CLDR backend module. The default
  is `Cldr.default_backend/0`.

* `:locale` is any locale returned by `Cldr.known_locale_names/1`
  or a `Cldr.LanguageTag.t`. The default is `options[:backend].get_locale/1`.

* `:number_system`: determines which of the number systems for a locale
  should be used to identify the separators and digits in the parsed
  number. If `number_system` is an `atom` then `number_system` is
  interpreted as a number system. See
  `Cldr.Number.System.number_systems_for/2`. If the `:number_system` is
  `binary` then it is interpreted as a number system name. See
  `Cldr.Number.System.number_system_names_for/2`. The default is to use
  the number system returned from `Cldr.Number.System.number_system_from_locale/2`.

* `:separators` selects which of the optional
  alternative grouping and decimal separators should be used
  when scanning. The default is `:standard`. To see what other
  separator variants may be avaialble in a given locale and
  number system, see `Cldr.Number.Symbol.number_symbols_for/2`.

## Returns

* A number of the requested or default type or

* `{:error, {exception, message}}` if no number could be determined

## Notes

This function parses a string to return a number but
in a locale-aware manner. It will normalise digits,
grouping characters and decimal separators.

It will transliterate digits that are in the
number system of the specific locale. For example, if
the locale is `th` (Thailand), then Thai digits are
transliterated to the Latin script before parsing.

Some number systems do not have decimal digits and in this
case an error will be returned, rather than continue
parsing and return misleading results.

It also caters for different forms of
the `+` and `-` symbols that appear in Unicode and
strips any `_` characters that might be used for
formatting in a string.

It then parses the number using the Elixir standard
library functions.

If the option `:number` is used and the parsed number
cannot be coerced to this type without losing precision
then an error is returned.

## Examples

    iex> Cldr.Number.Parser.parse("＋1.000,34", locale: :de)
    {:ok, 1000.34}

    iex> Cldr.Number.Parser.parse("-1_000_000.34")
    {:ok, -1000000.34}

    iex> Cldr.Number.Parser.parse("1.000", locale: :de, number: :integer)
    {:ok, 1000}

    iex> Cldr.Number.Parser.parse "١٢٣٤٥", locale: :"ar-EG"
    {:ok, 12345}

    iex> Cldr.Number.Parser.parse "١٢٣٤٥", locale: :ar, number_system: :arab
    {:ok, 12345}

    # 1_000.34 cannot be coerced into an integer
    # without precision loss so an error is returned.
    iex> Cldr.Number.Parser.parse("＋1.000,34", locale: :de, number: :integer)
    {:error,
      {Cldr.Number.ParseError,
       "The string \"＋1.000,34\" could not be parsed as a number"}}

    iex> Cldr.Number.Parser.parse "一万二千三百四十五", locale: "ja-u-nu-jpan"
    {:error, {Cldr.UnknownNumberSystemError, "The number system :jpan does not have digits"}}

# `remove_whitespace_between_tokens`

Removes any whitespace strings from between
tokens in a list.

Tokens are numbers or atoms.

# `resolve`

```elixir
@spec resolve([any()], fun(), Keyword.t()) :: list()
```

Maps a list of terms (usually strings and atoms)
calling a resolver function that operates
on each binary term.

If the resolver function returns `{:error, term}`
then no change is made to the term, otherwise
the return value of the resolver replaces the
original term.

## Arguments

* `list` is a list of terms. Typically this is the
  result of calling `Cldr.Number.Parser.scan/1`.

* `resolver` is a function that takes two
  arguments. The first is one of the terms
  in the `list`. The second is `options`.

* `options` is a keyword list of options
  that is passed to the resolver function.

## Note

* The resolver is called only on binary
  elements of the list.

## Returns

* `list` as modified through the application
  of the resolver function on each binary term.

## Examples

See `Cldr.Number.Parser.resolve_currencies/2` and
`Cldr.Number.Parser.resolve_pers/2` which both
use this function.

# `resolve_currencies`

```elixir
@spec resolve_currencies([String.t(), ...], Keyword.t()) :: [
  Cldr.Currency.currency_code() | String.t()
]
```

Resolve curencies from strings within
a list.

Currencies can be identified at the
beginning and/or the end of a string.

## Arguments

* `list` is any list in which currency
  names and symbols are expected

* `options` is a keyword list of options

## Options

* `:backend` is any module() that includes `use Cldr` and therefore
  is a `Cldr` backend module(). The default is `Cldr.default_backend!/0`.

* `:locale` is any valid locale returned by `Cldr.known_locale_names/1`
  or a `t:Cldr.LanguageTag` struct returned by `Cldr.Locale.new!/2`
  The default is `options[:backend].get_locale()`.

* `:separators` selects which of the optional
  alternative grouping and decimal separators should be used
  when scanning. The default is `:standard`. To see what other
  separator variants may be avaialble in a given locale and
  number system, see `Cldr.Number.Symbol.number_symbols_for/2`.

* `:only` is an `atom` or list of `atoms` representing the
  currencies or currency types to be considered for a match.
  The equates to a list of acceptable currencies for parsing.
  See the notes below for currency types.

* `:except` is an `atom` or list of `atoms` representing the
  currencies or currency types to be not considered for a match.
  This equates to a list of unacceptable currencies for parsing.
  See the notes below for currency types.

* `:fuzzy` is a float greater than `0.0` and less than or
  equal to `1.0` which is used as input to
  `String.jaro_distance/2` to determine is the provided
  currency string is *close enough* to a known currency
  string for it to identify definitively a currency code.
  It is recommended to use numbers greater than `0.8` in
  order to reduce false positives.

## Returns

* An ISO4217 currency code as an atom or

* `{:error, {exception, message}}`

## Notes

The `:only` and `:except` options accept a list of
currency codes and/or currency types.  The following
types are recognised.

If both `:only` and `:except` are specified,
the `:except` entries take priority - that means
any entries in `:except` are removed from the `:only`
entries.

  * `:all`, the default, considers all currencies

  * `:current` considers those currencies that have a `:to`
    date of nil and which also is a known ISO4217 currency

  * `:historic` is the opposite of `:current`

  * `:tender` considers currencies that are legal tender

  * `:unannotated` considers currencies that don't have
    "(some string)" in their names.  These are usually
    financial instruments.

## Examples

    iex> Cldr.Number.Parser.scan("100 US dollars")
    ...> |> Cldr.Number.Parser.resolve_currencies
    [100, :USD]

    iex> Cldr.Number.Parser.scan("100 eurosports")
    ...> |> Cldr.Number.Parser.resolve_currencies(fuzzy: 0.8)
    [100, :EUR]

    iex> Cldr.Number.Parser.scan("100 dollars des États-Unis")
    ...> |> Cldr.Number.Parser.resolve_currencies(locale: "fr")
    [100, :USD]

# `resolve_currency`

```elixir
@spec resolve_currency(String.t(), Keyword.t()) ::
  Cldr.Currency.currency_code()
  | [Cldr.Currency.currency_code() | String.t()]
  | {:error, {module(), String.t()}}
```

Resolve a currency from the beginning
and/or the end of a string

## Arguments

* `list` is any list in which currency
  names and symbols are expected

* `options` is a keyword list of options

## Options

* `:backend` is any module() that includes `use Cldr` and therefore
  is a `Cldr` backend module(). The default is `Cldr.default_backend!/0`

* `:locale` is any valid locale returned by `Cldr.known_locale_names/1`
  or a `Cldr.LanguageTag` struct returned by `Cldr.Locale.new!/2`
  The default is `options[:backend].get_locale()`

* `:only` is an `atom` or list of `atoms` representing the
  currencies or currency types to be considered for a match.
  The equates to a list of acceptable currencies for parsing.
  See the notes below for currency types.

* `:except` is an `atom` or list of `atoms` representing the
  currencies or currency types to be not considered for a match.
  This equates to a list of unacceptable currencies for parsing.
  See the notes below for currency types.

* `:fuzzy` is a float greater than `0.0` and less than or
  equal to `1.0` which is used as input to
  `String.jaro_distance/2` to determine is the provided
  currency string is *close enough* to a known currency
  string for it to identify definitively a currency code.
  It is recommended to use numbers greater than `0.8` in
  order to reduce false positives.

## Returns

* An ISO417 currency code as an atom or

* `{:error, {exception, message}}`

## Notes

The `:only` and `:except` options accept a list of
currency codes and/or currency types.  The following
types are recognised.

If both `:only` and `:except` are specified,
the `:except` entries take priority - that means
any entries in `:except` are removed from the `:only`
entries.

  * `:all`, the default, considers all currencies

  * `:current` considers those currencies that have a `:to`
    date of nil and which also is a known ISO4217 currency

  * `:historic` is the opposite of `:current`

  * `:tender` considers currencies that are legal tender

  * `:unannotated` considers currencies that don't have
    "(some string)" in their names.  These are usually
    financial instruments.

## Examples

    iex> Cldr.Number.Parser.resolve_currency("US dollars")
    [:USD]

    iex> Cldr.Number.Parser.resolve_currency("100 eurosports", fuzzy: 0.75)
    [:EUR]

    iex> Cldr.Number.Parser.resolve_currency("dollars des États-Unis", locale: "fr")
    [:USD]

    iex> Cldr.Number.Parser.resolve_currency("not a known currency", locale: "fr")
    {:error,
     {Cldr.UnknownCurrencyError,
      "The currency \"not a known currency\" is unknown or not supported"}}

# `resolve_per`
*since 2.21.0* 

```elixir
@spec resolve_per(String.t(), Keyword.t()) ::
  per() | [per() | String.t()] | {:error, {module(), String.t()}}
```

Resolve and tokenize percent or permille
from the beginning and/or the end of a string

## Arguments

* `list` is any list in which percent
  and permille symbols are expected

* `options` is a keyword list of options

## Options

* `:backend` is any module() that includes `use Cldr` and therefore
  is a `Cldr` backend module(). The default is `Cldr.default_backend!/0`

* `:locale` is any valid locale returned by `Cldr.known_locale_names/1`
  or a `Cldr.LanguageTag` struct returned by `Cldr.Locale.new!/2`
  The default is `options[:backend].get_locale()`

## Returns

* An `:percent` or `permille` or

* `{:error, {exception, message}}`

## Examples

    iex> Cldr.Number.Parser.resolve_per "11%"
    ["11", :percent]

    iex> Cldr.Number.Parser.resolve_per "% of linguists"
    [:percent, " of linguists"]

    iex> Cldr.Number.Parser.resolve_per "% of linguists %"
    [:percent, " of linguists ", :percent]

# `resolve_pers`
*since 2.21.0* 

```elixir
@spec resolve_pers([String.t(), ...], Keyword.t()) :: [per() | String.t()]
```

Resolve and tokenize percent and permille
sybols from strings within a list.

Percent and permille symbols can be identified
at the beginning and/or the end of a string.

## Arguments

* `list` is any list in which percent and
  permille symbols are expected

* `options` is a keyword list of options

## Options

* `:backend` is any module() that includes `use Cldr` and therefore
  is a `Cldr` backend module(). The default is `Cldr.default_backend!/0`

* `:locale` is any valid locale returned by `Cldr.known_locale_names/1`
  or a `t:Cldr.LanguageTag` struct returned by `Cldr.Locale.new!/2`
  The default is `options[:backend].get_locale()`

## Examples

    iex> Cldr.Number.Parser.scan("100%")
    ...> |> Cldr.Number.Parser.resolve_pers()
    [100, :percent]

# `scan`

```elixir
@spec scan(String.t(), Keyword.t()) ::
  [String.t() | integer() | float() | Decimal.t()]
  | {:error, {module(), String.t()}}
```

Scans a string in a locale-aware manner and returns
a list of strings and numbers.

## Arguments

* `string` is any `String.t`

* `options` is a keyword list of options

## Options

* `:number` is one of `:integer`, `:float`,
  `:decimal` or `nil`. The default is `nil`
  meaning that the type auto-detected as either
  an `integer` or a `float`.

* `:backend` is any module that includes `use Cldr`
  and is therefore a CLDR backend module. The default
  is `Cldr.default_backend!/0`.

* `:locale` is any locale returned by `Cldr.known_locale_names/1`
  or a `t:Cldr.LanguageTag`. The default is `options[:backend].get_locale/1`.

* `:number_system`: determines which of the number systems for a locale
  should be used to identify the separators and digits in the parsed
  number. If `number_system` is an `atom` then `number_system` is
  interpreted as a number system. See
  `Cldr.Number.System.number_systems_for/2`. If the `:number_system` is
  `binary` then it is interpreted as a number system name. See
  `Cldr.Number.System.number_system_names_for/2`. The default is to use
  the number system returned from `Cldr.Number.System.number_system_from_locale/2`.

* `:separators` selects which of the optional
  alternative grouping and decimal separators should be used
  when scanning. The default is `:standard`. To see what other
  separator variants may be avaialble in a given locale and
  number system, see `Cldr.Number.Symbol.number_symbols_for/3`.

## Returns

* A list of strings and numbers

## Notes

Number parsing is performed by `Cldr.Number.Parser.parse/2`
and any options provided are passed to that function.

## Examples

    iex> Cldr.Number.Parser.scan("£1_000_000.34")
    ["£", 1000000.34]

    iex> Cldr.Number.Parser.scan("I want £1_000_000 dollars")
    ["I want £", 1000000, " dollars"]

    iex> Cldr.Number.Parser.scan("The prize is 23")
    ["The prize is ", 23]

    iex> Cldr.Number.Parser.scan("The lottery number is 23 for the next draw")
    ["The lottery number is ", 23, " for the next draw"]

    iex> Cldr.Number.Parser.scan("The loss is -1.000 euros", locale: :de, number: :integer)
    ["The loss is ", -1000, " euros"]

    iex> Cldr.Number.Parser.scan("1kg")
    [1, "kg"]

    iex> Cldr.Number.Parser.scan("A number is the arab script ١٢٣٤٥", locale: "ar", number_system: :arab)
    ["A number is the arab script ", 12345]

    iex> Cldr.Number.Parser.scan("A number is the arab script ١٢٣٤٥", locale: "ar-u-nu-arab")
    ["A number is the arab script ", 12345]

---

*Consult [api-reference.md](api-reference.md) for complete listing*