defmodule Cldr.Number.Parser do
@moduledoc """
Functions for parsing numbers and currencies from
a string.
"""
@type per :: :percent | :permille
@number_format "[-+]?[0-9]([0-9_]|[,](?=[0-9]))*(\\.?[0-9_]+([eE][-+]?[0-9]+)?)?"
@doc """
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`.
## 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"
["A number is the arab script ", 12345]
"""
@spec scan(String.t(), Keyword.t()) ::
list(String.t() | integer() | float() | Decimal.t())
| {:error, {module(), String.t()}}
def scan(string, options \\ []) do
{locale, backend} = Cldr.locale_and_backend_from(options)
with {:ok, locale} <- Cldr.validate_locale(locale, backend),
{:ok, symbols} <- Cldr.Number.Symbol.number_symbols_for(locale, backend),
{:ok, number_system} <- digits_number_system_from(locale) do
symbols = symbols_for_number_system(symbols, number_system)
scanner =
@number_format
|> localize_format_string(locale, backend, symbols)
|> Regex.compile!([:unicode])
normalized_string = transliterate(string, number_system, :latn, backend)
scanner
|> Regex.split(normalized_string, include_captures: true, trim: true)
|> Enum.map(&parse_element(&1, options))
end
end
defp parse_element(element, options) do
case parse(element, options) do
{:ok, number} -> number
{:error, _} -> element
end
end
@doc """
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`.
## 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"
{: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"}}
"""
@spec parse(String.t(), Keyword.t()) ::
{:ok, integer() | float() | Decimal.t()}
| {:error, {module(), String.t()}}
def parse(string, options \\ []) when is_binary(string) and is_list(options) do
{locale, backend} = Cldr.locale_and_backend_from(options)
with {:ok, locale} <- Cldr.validate_locale(locale, backend),
{:ok, symbols} <- Cldr.Number.Symbol.number_symbols_for(locale, backend),
{:ok, number_system} <- digits_number_system_from(locale) do
symbols = symbols_for_number_system(symbols, number_system)
normalized_string =
string
|> transliterate(number_system, :latn, backend)
|> normalize_number_string(locale, backend, symbols)
|> String.trim()
case parse_number(normalized_string, Keyword.get(options, :number)) do
{:error, _} -> {:error, parse_error(string)}
success -> success
end
end
end
defp parse_number(string, nil) do
with {:error, string} <- parse_number(string, :integer),
{:error, string} <- parse_number(string, :float) do
{:error, string}
end
end
defp parse_number(string, :integer) do
case Integer.parse(string) do
{integer, ""} -> {:ok, integer}
_other -> {:error, string}
end
end
defp parse_number(string, :float) do
case Float.parse(string) do
{float, ""} -> {:ok, float}
_other -> {:error, string}
end
end
defp parse_number(string, :decimal) do
case Cldr.Decimal.parse(string) do
{:error, ""} -> {:error, string}
{decimal, ""} -> {:ok, decimal}
_other -> {:error, string}
end
end
@doc """
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()`
* `: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]
"""
@spec resolve_currencies([String.t(), ...], Keyword.t()) ::
list(Cldr.Currency.code() | String.t())
def resolve_currencies(list, options \\ []) when is_list(list) and is_list(options) do
resolve(list, &resolve_currency/2, options)
end
@doc """
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]
"""
@doc since: "2.21.0"
@spec resolve_pers([String.t(), ...], Keyword.t()) ::
list(per() | String.t())
def resolve_pers(list, options \\ []) when is_list(list) and is_list(options) do
resolve(list, &resolve_per/2, options)
end
@doc """
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.
"""
@spec resolve(list(any()), fun(), Keyword.t()) :: list()
def resolve(list, resolver, options) do
Enum.map(list, fn
string when is_binary(string) ->
case resolver.(string, options) do
{:error, _} -> string
other -> other
end
other ->
other
end)
|> List.flatten()
end
@doc false
defguard is_token(arg) when is_atom(arg) or is_number(arg)
@doc """
Removes any whitespace strings from between
tokens in a list.
Tokens are numbers or atoms.
"""
@whitespace ~r/^\s*$/u
def remove_whitespace_between_tokens([first, second, third | rest])
when is_token(first) and is_token(third) do
if String.match?(second, @whitespace) do
[first | remove_whitespace_between_tokens([third | rest])]
else
[first | remove_whitespace_between_tokens([second, third | rest])]
end
end
def remove_whitespace_between_tokens([first | rest]) do
[first | remove_whitespace_between_tokens(rest)]
end
def remove_whitespace_between_tokens(first) do
first
end
@doc """
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"}}
"""
@spec resolve_currency(String.t(), Keyword.t()) ::
Cldr.Currency.code()
| list(Cldr.Currency.code() | String.t())
| {:error, {module(), String.t()}}
def resolve_currency(string, options \\ []) when is_binary(string) do
{locale, backend} = Cldr.locale_and_backend_from(options)
{only_filter, options} =
Keyword.pop(options, :only, Keyword.get(options, :currency_filter, [:all]))
{except_filter, options} = Keyword.pop(options, :except, [])
{fuzzy, _options} = Keyword.pop(options, :fuzzy, nil)
with {:ok, locale} <- backend.validate_locale(locale),
{:ok, currency_strings} <-
Cldr.Currency.currency_strings(locale, backend, only_filter, except_filter),
{:ok, currency} <- find_and_replace(currency_strings, string, fuzzy) do
currency
else
{:error, {Cldr.Number.ParseError, _}} ->
{:error, unknown_currency_error(string)}
other ->
other
end
end
@doc """
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]
"""
@doc since: "2.21.0"
@spec resolve_per(String.t(), Keyword.t()) ::
per() | list(per() | String.t()) | {:error, {module(), String.t()}}
def resolve_per(string, options \\ []) when is_binary(string) do
{locale, backend} = Cldr.locale_and_backend_from(options)
{fuzzy, _options} = Keyword.pop(options, :fuzzy, nil)
with {:ok, locale} <- backend.validate_locale(locale),
{:ok, per_strings} <- per_strings(locale, backend),
{:ok, per} <- find_and_replace(per_strings, string, fuzzy) do
per
else
{:error, {Cldr.Number.ParseError, _}} ->
{:error, {Cldr.Number.ParseError, "No percent or permille found"}}
other ->
other
end
end
defp per_strings(locale, backend) do
with {:ok, number_system} <- digits_number_system_from(locale),
{:ok, symbols} <- Cldr.Number.Symbol.number_symbols_for(locale, backend) do
symbols = symbols_for_number_system(symbols, number_system)
parse_map = backend.lenient_parse_map(:general, locale.cldr_locale_name)
{:ok,
Map.new(per_map(parse_map, symbols.percent_sign) ++ per_map(parse_map, symbols.per_mille))}
end
end
defp per_map(parse_map, char) do
parse_map
|> Map.fetch!(char)
|> Map.fetch!(:source)
|> String.replace("[", "")
|> String.replace("]", "")
|> String.graphemes()
|> Enum.map(&{&1, :percent})
end
# Replace localised symbols with canonical forms
defp normalize_number_string(string, locale, backend, symbols) do
string
|> String.replace("_", "")
|> backend.normalize_lenient_parse(:number, locale)
|> backend.normalize_lenient_parse(:general, locale)
|> String.replace(symbols.group, "")
|> String.replace(" ", "")
|> String.replace(symbols.decimal, ".")
|> String.replace("_", "-")
end
defp transliterate(string, from, to, backend) do
module = Module.concat(backend, Number.Transliterate)
case module.transliterate_digits(string, from, to) do
{:error, _} -> string
string -> string
end
end
defp digits_number_system_from(locale) do
number_system = Cldr.Number.System.number_system_from_locale(locale)
with {:ok, _digits} <- Cldr.Number.System.number_system_digits(number_system) do
{:ok, number_system}
end
end
defp symbols_for_number_system(symbols, number_system) do
Map.fetch!(symbols, number_system) || Map.fetch!(symbols, :latn)
end
# Replace canonical forms with localised symbols
defp localize_format_string(string, locale, backend, symbols) do
parse_map = backend.lenient_parse_map(:number, locale.cldr_locale_name)
plus_matchers = Map.get(parse_map, "+").source |> String.replace(["[", "]"], "")
minus_matchers = Map.get(parse_map, "_").source |> String.replace(["[", "]"], "")
grouping_matchers = Map.get(parse_map, ",").source |> String.replace(["[", "]"], "")
string
|> String.replace("[-+]", "[" <> plus_matchers <> minus_matchers <> "]")
|> String.replace(",", grouping_matchers <> maybe_add_space(symbols.group))
|> String.replace("\\.", "\\" <> symbols.decimal)
end
# If the grouping symbol is a pop space then
# also allow normal space as a group symbol when parsing
# 0x202c
@pop_space " "
# 0x20
@space " "
defp maybe_add_space(@pop_space), do: @pop_space <> @space
defp maybe_add_space(other), do: other
@doc """
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"}}
"""
@doc since: "2.22.0"
@spec find_and_replace(%{binary() => term()}, binary(), float() | nil) ::
{:ok, list()} | {:error, {module(), binary()}}
def find_and_replace(string_map, string, fuzzy \\ nil)
def find_and_replace(string_map, string, fuzzy) when is_map(string_map) and is_binary(string) do
if String.trim(string) == "" do
{:ok, string}
else
do_find_and_replace(string_map, string, fuzzy)
end
end
defp do_find_and_replace(string_map, string, nil)
when is_map(string_map) and is_binary(string) do
if code = Map.get(string_map, normalize_search_string(string)) do
{:ok, [code]}
else
[starting_code, remainder] = starting_string(string_map, string)
[remainder, ending_code] = ending_string(string_map, remainder)
if starting_code == "" && ending_code == "" do
{:error, {Cldr.Number.ParseError, "No match was found"}}
else
{:ok, Enum.reject([starting_code, remainder, ending_code], &(&1 == ""))}
end
end
end
defp do_find_and_replace(string_map, search, fuzzy)
when is_float(fuzzy) and fuzzy > 0.0 and fuzzy <= 1.0 do
canonical_search = String.downcase(search)
{distance, code} =
string_map
|> Enum.map(fn {k, v} -> {String.jaro_distance(k, canonical_search), v} end)
|> Enum.sort(fn {k1, _v1}, {k2, _v2} -> k1 > k2 end)
|> hd
if distance >= fuzzy do
{:ok, [code]}
else
{:error, {Cldr.Number.ParseError, "No match was found"}}
end
end
defp do_find_and_replace(_currency_strings, _currency, fuzzy) do
{:error,
{
ArgumentError,
"option :fuzzy must be a number > 0.0 and <= 1.0. Found #{inspect(fuzzy)}"
}}
end
defp starting_string(string_map, search) do
[whitespace, trimmed] =
search
|> String.downcase()
|> String.split(~r/^\s*/, parts: 2, include_captures: true, trim: true)
case starts_with(string_map, trimmed) do
[] ->
["", search]
list ->
{string, match_length, code} = longest_match(list)
[_, remainder] = String.split(trimmed, string, parts: 2)
if String.match?(remainder, ~r/^[[:alpha:]]/u) do
["", search]
else
match_length = match_length + :erlang.byte_size(whitespace)
<<_::binary-size(match_length), remainder::binary>> = search
[code, remainder]
end
end
end
defp ending_string(string_map, search) do
trimmed =
search
|> String.downcase()
|> String.trim_trailing()
case ends_with(string_map, trimmed) do
[] ->
[search, ""]
list ->
{string, match_length, code} = longest_match(list)
[remainder, _] = String.split(trimmed, string, parts: 2)
if String.match?(remainder, ~r/[[:alpha:]]$/u) do
[search, ""]
else
match = :erlang.byte_size(trimmed) - match_length
<<remainder::binary-size(match), _rest::binary>> = search
[remainder, code]
end
end
end
defp normalize_search_string(string) do
string
|> String.downcase()
|> String.trim()
end
defp starts_with(strings, search) do
Enum.filter(strings, &String.starts_with?(search, elem(&1, 0)))
end
defp ends_with(strings, search) do
Enum.filter(strings, &String.ends_with?(search, elem(&1, 0)))
end
defp longest_match(matches) do
{match, code} =
matches
|> Enum.sort(fn a, b -> String.length(elem(a, 0)) > String.length(elem(b, 0)) end)
|> hd
{match, :erlang.byte_size(match), code}
end
defp unknown_currency_error(currency) do
{Cldr.UnknownCurrencyError, "The currency #{inspect(currency)} is unknown or not supported"}
end
defp parse_error(string) do
{Cldr.Number.ParseError, "The string #{inspect(string)} could not be parsed as a number"}
end
end
