Decimal.parse

Decimal.parse reads the complete input string. Text starts with an optional ASCII plus or minus sign. The remaining text contains ASCII digits and at most one decimal point.

Without a decimal point, at least one digit is required. With a decimal point, at least one digit must follow it and the integer digits may be absent. The strings .5 and -.5 are accepted. The strings 1. and . are rejected.

Leading integer zeros and trailing fractional zeros are accepted. Their exact numeric value is normalized by the decimal value rule. An accepted sign on zero does not survive normalization.

The input may contain at most 4294967295 fractional digits before normalization. A larger fractional digit count returns None(). The integer digit count has no fixed numeric precision limit.

Whitespace, non-ASCII digits, separators, radix prefixes, exponents, NaN and infinity spellings are rejected. Parsing does not trim, remove separators, stop at a valid prefix, or convert through a binary float.

Valid text returns Some containing the exact Decimal. Every malformed spelling returns None() without a numeric conversion fault or replacement value.

This grammar describes text data passed to Decimal.parse. Numeric literal spelling follows the language literal rules.