expr_syntax

evalexpr  := subexpr
subexpr   := expcomma
expcomma  := expassign *, exprassign*
expassign := expcond [=|+=|-= ... ] expassign
expcond   := explor [? expcomma : expcond ]
explor    := expland * || expland  *
expland   := expbor  * && expbor   *
expbor    := expbxor * |  expbxor  *
expbxor   := expband * ^   expband *
expband   := exp5    * &   exp5    *
exp5      := exp4 * [==|!=] exp4   *
exp4      := expshift * [<|<=|>|>=] expshift *
expshift  := exp3 * [<<|>>] exp3   *
exp3      := exp2 * [+|-] exp2     *
exp2      := exppower * [*|/|%] exppower *
exppower  := exp1 * ** exppower *
exp1      := [!|~|-|+] exp1 | exp0
exp0      := [++|--] ARRAY  | ( expcomma ) | NUM | exppost 
exppost   := ARRAY [ [++|--] ]
array     := VAR [ [ expcomma ] ]