Arithmetic expansion semantics (POSIX portability)

[magicant]

• Arithmetic expansion basics #170
• Implement yash-arith/src/lib.rs
  • Primary terms in arithmetic expansion #171
    • Implement and test error handling in yash-semantics/src/expansion/initial/arith.rs
  • Binary operators in arithmetic expansion #172
  • Conditional binary operators in arithmetic expansion #173
  • Unary operators in arithmetic expansion #175
  • Conditional operator in arithmetic expansion #177
  • Assignment operators
  • Documentation
  • (Review remaining todos)
    • Error handling in arithmetic expansion #180
  • (Refactoring)
    • Separate parsing and evaluation in arithmetic expansion #178
• Apply nounset option in arithmetic expansion #263

For non-portable extensions to the arithmetic expansion semantics, see #261.

[magicant]

Syntax of arithmetic expansion:

AssignmentExp := ConditionalExp
               | ConditionalExp AssignmentOperator AssignmentExp;
ConditionalExp := LogicalOrExp
                | LogicalOrExp "?" AssignmentExp ":" ConditionalExp;
LogicalOrExp := LogicalAndExp | LogicalOrExp "||" LogicalAndExp;
LogicalAndExp := InclusiveOrExp | LogicalAndExp "&&" InclusiveOrExp;
InclusiveOrExp := ExclusiveOrExp | InclusiveOrExp "|" ExclusiveOrExp;
ExclusiveOrExp := AndExp | ExclusiveOrExp "^" AndExp;
AndExp := EqualityExp | AndExp "&" EqualityExp;
EqualityExp := RelationalExp
             | EqualityExp "==" RelationalExp
             | EqualityExp "!=" RelationalExp;
RelationalExp := ShiftExp
               | RelationalExp "<" ShiftExp
               | RelationalExp ">" ShiftExp
               | RelationalExp "<=" ShiftExp
               | RelationalExp ">=" ShiftExp;
ShiftExp := AdditiveExp
          | ShiftExp "<<" AdditiveExp | ShiftExp ">>" AdditiveExp;
AdditiveExp := MultiplicativeExp
             | AdditiveExp "+" MultiplicativeExp
             | AdditiveExp "-" MultiplicativeExp;
MultiplicativeExp := PrefixExp
                   | MultiplicativeExp "*" PrefixExp
                   | MultiplicativeExp "/" PrefixExp
                   | MultiplicativeExp "%" PrefixExp;
PrefixExp := PostfixExp
           | "++" PrefixExp | "--" PrefixExp
           | "+" PrefixExp | "-" PrefixExp
           | "~" PrefixExp | "!" PrefixExp;
PostfixExp := PrimaryExp
            | PostfixExp "++" | PostfixExp "--";
PrimaryExp := "(" AssignmentExp ")" | Number | Identifier;

---

Operators:

Precedence	Associativity	Operators
0	Enclosing	) :
1	Right	=, *=, /=, %=, +=, -=, <<=, >>=, &=, ^=, |=
2	Right	?
3	Left	||
4	Left	&&
5	Left	|
6	Left	^
7	Left	&
8	Left	==, !=
9	Left	<, >, <=, >=
10	Left	<<, >>
11	Left	+, -
12	Left	*, /, %
13	Prefix	++, --, +, -, ~, !
14	Postfix	++, --
15	Enclosing	(