Trait pw_format::macros::PrintfFormatMacroGenerator

pub trait PrintfFormatMacroGenerator {
    // Required methods
    fn finalize(
        self,
        format_string_fragments: &[PrintfFormatStringFragment]
    ) -> Result<TokenStream>;
    fn string_fragment(&mut self, string: &str) -> Result<()>;
    fn integer_conversion(
        &mut self,
        ty: Ident,
        expression: Arg
    ) -> Result<Option<String>>;
    fn string_conversion(&mut self, expression: Arg) -> Result<Option<String>>;
    fn char_conversion(&mut self, expression: Arg) -> Result<Option<String>>;

    // Provided method
    fn untyped_conversion(&mut self, _expression: Arg) -> Result<()> { ... }
}

A specialized generator for proc macros that produce printf style format strings.

For proc macros that need to translate a pw_format invocation into a printf style format string, PrintfFormatMacroGenerator offer a specialized form of FormatMacroGenerator that builds the format string and provides it as an argument to finalize.

In cases where a generator needs to override the conversion specifier it can return it from its appropriate conversion method. An example of using this would be wanting to pass a Rust string directly to a printf call over FFI. In that case, string_conversion could return Ok(Some("%.*s".to_string())) to allow both the length and string pointer to be passed to printf.

Required Methods

fn finalize( self, format_string_fragments: &[PrintfFormatStringFragment] ) -> Result<TokenStream>

Called by generate_printf at the end of code generation.

Works like FormatMacroGenerator::finalize with the addition of being provided a printf_style format string.

fn string_fragment(&mut self, string: &str) -> Result<()>

Process a string fragment.

NOTE: This string may contain unescaped % characters. However, most implementations of this train can simply ignore string fragments as they will be included (with properly escaped % characters) as part of the format string passed to PrintfFormatMacroGenerator::finalize.

See FormatMacroGenerator::string_fragment for a disambiguation between a string fragment and string conversion.

fn integer_conversion( &mut self, ty: Ident, expression: Arg ) -> Result<Option<String>>

Process an integer conversion.

May optionally return a printf format string (i.e. “%d”) to override the default.

fn string_conversion(&mut self, expression: Arg) -> Result<Option<String>>

Process a string conversion.

May optionally return a printf format string (i.e. “%s”) to override the default.

See FormatMacroGenerator::string_fragment for a disambiguation between a string fragment and string conversion.

fn char_conversion(&mut self, expression: Arg) -> Result<Option<String>>

Process a character conversion.

May optionally return a printf format string (i.e. “%c”) to override the default.

Provided Methods

fn untyped_conversion(&mut self, _expression: Arg) -> Result<()>

Process and untyped conversion.

Implementors