NumberParser

Proves invariant text parsing into one exact numeric representation. Built-in integer/IEEE types bind their existing exact source parser. Custom types may provide the same static member. Parsing returns owned values and retains no text backing; syntax/range policies are explicit in ParseError. This concept grants no lifecycle permission, allocation or runtime witness.

Module std.text

import std.text;

Public declaration contracts and authored examples. A page can document several related symbols. Implementation bodies are excluded.

NumberParser

pub concept NumberParser<Self>

Example

module example.number_parser;
from std.text import NumberParser, ParseError;
from std.prelude import Result;
fn ParseInvariant<T>(Text: str) -> Result<T, ParseError> where T: NumberParser, Defaultable {
    return T.ParseNumber(Text, default(T));
}
fn Main() -> i32 {
    switch ParseInvariant<i32>("42") {
        case .Ok { Value = Value } => { if Value != 42 { return 1; } }
        case .Err { Error = _ } => return 2;
    }
    switch ParseInvariant<i32>("42x") {
        case .Ok { Value = _ } => return 3;
        case .Err { Error = Error } => { if Error != ParseError.InvalidSyntax { return 4; } }
    }
    switch ParseInvariant<i8>("128") {
        case .Ok { Value = _ } => return 5;
        case .Err { Error = Error } => { if Error != ParseError.OutOfRange { return 6; } }
    }
    return 0;
}

Example

module example.floating_parsing;
from std.text import TryParse, ParseError;
fn Main() -> i32 {
    switch TryParse<f16>("0.1") {
        case .Ok { Value = Value } => {
            if bit_cast<u16>(Value) != 0x2E66_u16 { return 1; }
        }
        case .Err { Error = _ } => return 2;
    }
    switch TryParse<f64>("-0") {
        case .Ok { Value = Value } => {
            if bit_cast<u64>(Value) != 0x8000000000000000_u64 { return 3; }
        }
        case .Err { Error = _ } => return 4;
    }
    switch TryParse<f32>("1.0 trailing") {
        case .Ok { Value = _ } => return 5;
        case .Err { Error = Error } => {
            if Error != ParseError.InvalidSyntax { return 6; }
        }
    }
    return 0;
}

NumberParser.ParseNumber

requires static fn ParseNumber(Text: str, Witness: Self) -> Result<Self, ParseError>;

Parses one complete invariant numeric token without retaining input. Text: UTF8 input borrowed through the call. Witness: Exact type witness. Return: Owned value, InvalidSyntax or OutOfRange.