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143 lines
2.8 KiB
Markdown
143 lines
2.8 KiB
Markdown
---
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title: "string_stream"
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---
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## Streaming types
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`string_stream`
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`wstring_stream`
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`u16string_stream`
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`u32string_stream`
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Classes to build strings using a streaming API.
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Uses `etl::basic_format_spec` to define the required formatting.
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The documentation below is for `etl::string_stream`.
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The other streams have a similar API, though using `w`, `u8`, `u16` or `u32` types.
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## Member functions
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```cpp
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explicit string_stream(etl::istring& str)
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```
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**Description**
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Construct, using the supplied string as a buffer.
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Uses the default `format_spec`.
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---
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```cpp
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string_stream(etl::istring& str, const etl::format_spec& spec)
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```
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**Description**
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Construct, using the supplied string as a buffer.
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Initialised with the supplied `format_spec`.
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---
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```cpp
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void set_format(const etl::format_spec& spec_)
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```
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**Description**
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Sets a new `format_spec` to use.
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---
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```cpp
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const etl::format_spec& get_format() const
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```
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**Description**
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Gets the current `format_spec`.
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---
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```cpp
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etl::istring& str()
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```
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**Description**
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Gets a reference to the internal string.
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```cpp
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const etl::istring& str() const
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```
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**Description**
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Gets a const reference to the internal string.
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---
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```cpp
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void str(const etl::istring::const_pointer p)
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```
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**Description**
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Resets the internal string to the text pointed to by `p`.
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---
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```cpp
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void str(const etl::istring& text)
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```
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**Description**
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Resets the internal string to `text`.
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## Streaming operators
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```cpp
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string_stream& operator <<(string_stream& ss, T value)
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```
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**Description**
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Where `T` may be one of the following:-
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Any fundamental type.
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`etl::format_spec`
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`etl::setb0ase(n)`
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`etl::bin`
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`etl::oct`
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`etl::dec`
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`etl::hex`
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`etl::setfill(c)`
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`etl::setw(n)`
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`etl::setprecision(n)`
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`etl::left`
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`etl::right`
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`etl::boolalpha`
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`etl::noboolalpha`
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`etl::uppercase`
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`etl::nouppercase`
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`etl::showbase`
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`etl::noshowbase`
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`etl::string`
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`etl::istring`
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`etl::string_view`
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`const char*`
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See `etl::format_spec`
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Custom user types may be streamed by overloading the streaming operator.
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## Examples
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### Using format_spec
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```cpp
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etl::format_spec format1 = etl::format_spec().hex().width(8).fill('0');
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etl::format_spec format2;
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etl::format_spec format3 = etl::format_spec().width(6).fill('#').precision(3);
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etl::string<50> text;
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etl::string_stream stream(text);
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stream << format1 << 1193046 << format2 << " " << format3 << 3.1415;
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const etl::istring& result = stream.str();
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```
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`text` is set to `"00123456 #3.142"`.
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### Using stream manipulators
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```cpp
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etl::string<50> text;
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etl::string_stream stream(text);
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stream << etl::hex << etl::setw(8) << etl::setfill('0') << 1193046
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<< etl::setw(0) << " "
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<< etl::setw(6) << etl::setfill('#') << etl::setprecision(3) << 3.1415;
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const etl::istring& result = stream.str();
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```
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`text` is set to `"00123456 #3.142"`.
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