CxCodeUnit

// Comment

using Usings.First;
using Usings.Second;
...

#pragma ... (ignored)

// ... (ignored)

namespace Namespace
{
  class Declaration
  {
    ...
  }
}

#                := w ;
root             := code-unit ;

!code-unit       := comment? usings? (comment-line | pragma-line)* namespace ;

!comment         := comment-line comment-line* ;
!namespace       := 'namespace' w+ (id .. '.') '{' decl '}' ;
!pragma-line     := '#pragma' ~lb* lb ;
usings           := using using* ;

!decl            := xmldoc? attribs? modifiers (class | delegate | enum | interface
                    | struct) ;
!using           := 'using' w+ name ';' ;

!class           := 'class' w+ name-id type-params? base-types? constraints? regions ;
!delegate        := 'delegate' w+ var-decl type-params? params constraints? ';' ;
!enum            := 'enum' w+ name-id '{' (item .. comma) '}' ;
!interface       := 'interface' w+ name-id type-params? base-types? constraints?
                    regions ;
!struct          := 'struct' w+ name-id type-params? base-types? constraints?
                    regions ;

base-types       := ':' (type .. comma) ;
item             := xmldoc? name-id '=' expr ;
regions          := '{' region* '}' ;

region           := '#region' ws ~lb+ lb member* '#endregion' ;

member           := xmldoc? attribs? modifiers (constant | constructor | field
                    | indexer | method | operator | property) ;

!constant        := 'const' w+ var-def ';' ;
!constructor     := name-id params (':' 'base' '(' (expr .. comma)? ')')? stat-block ;
!field           := var ';' ;
!indexer         := type 'this' '[' var-decl ']' '{' getter? setter? '}' ;
!method          := var-decl type-params? params constraints? (stat-block | ';') ;
modifiers        := ('public' w+)? ('protected' w+)? ('internal' w+)? ('new' w+)?
                    ('abstract' w+)? ('virtual' w+)? ('override' w+)? ('sealed' w+)?
                    ('static' w+)? ('readonly' w+)? ('volatile' w+)? ('partial' w+)? ;
!operator        := type 'operator' operator-op params stat-block ;
!property        := var-decl '{' getter? setter? '}' ;
!xmldoc          := (ws* xmldoc-line)+ ;

constraints      := constraint constraint* ;
getter           := 'get' (';' | stat-block) ;
operator-op      := '==' | '!=' | '>=' | '<=' | '<<' | '>>' | '&' | '/'
                    | '>' | '~' | '<' | '%' | '*' | '-' | '!' | '|' | '+' | '^' ;
params           := '(' (param .. comma)? ')' ;
setter           := 'set' (';' | stat-block) ;
type-params      := '<' (type-param .. comma) '>' ;
xmldoc-line      := '///' (ws ]\n\r[*)? lb ;

constraint       := 'where' w+ name-id ':' (constraint-item .. comma)? ;
param            := attribs? (('ref' | 'out' | 'this') w+)? var ;
type-param       := (('in' | 'out') w+)? name-id ;

attribs          := '[' (attrib .. comma) ']' ;
constraint-item  := 'class' | 'struct' | 'new()' | type-generic ;

attrib           := name-id ('(' (expr .. comma) ')')? ;

!arg             := (('out' | 'ref') w+)? expr ;
expr             := expr-assign ;
!expr-add        := expr-mul !> (expr-add-op expr-mul)+ ;
!expr-assign     := expr-cond !> (expr-assign-op expr-cond)+ ;
!expr-brace      := '(' expr ')' ;
!expr-cond       := expr-cond-or !> '?' expr-cond ':' expr-cond ;
!expr-cond-and   := expr-logic-or !> ('&&' expr-logic-or)+ ;
!expr-cond-or    := expr-cond-and !> ('||' expr-cond-and)+ ;
!expr-default    := 'default' '(' type ')' ;
!expr-equal      := expr-relate !> expr-equal-op expr-relate ;
!expr-generic    := expr-name !> '<' (type .. comma) '>' ;
!expr-logic-and  := expr-equal !> ('&' expr-equal)+ ;
!expr-logic-or   := expr-logic-xor !> ('|' expr-logic-xor)+ ;
!expr-logic-xor  := expr-logic-and !> ('^' expr-logic-and)+ ;
!expr-mul        := expr-unary !> (expr-mul-op expr-unary)+ ;
!expr-new        := 'new' w+ type (expr-new-object | expr-new-array1
                    | expr-new-array2) ;
!expr-new-array1 := '{' (expr .. comma)? '}' ;
!expr-new-array2 := '[' expr ']' '[]'* ;
!expr-new-object := '(' (expr .. comma)? ')' ;
!expr-primary    := expr-brace | expr-new | expr-literal | expr-default
                    | expr-generic ;
!expr-relate     := expr-shift !> expr-relate-op expr-shift ;
!expr-shift      := expr-add !> (expr-shift-op expr-add)+ ;
!expr-suffix     := expr-primary !> expr-suffix-op+ ;
expr-suffix-op   := '(' (arg .. comma)? ')' | '.' expr-generic | '[' expr ']' | '++'
                    | '--' ;
!expr-unary      := expr-unary-op+ <! expr-suffix ;
expr-unary-op    := '++' | '+' | '--' | '-' \ literal-number | '!' | '~' | '(' type
                    ')' <expr> ;
for-cond         := expr ;
for-next         := expr (comma expr)* ;
stat             := stat-block | stat-debug | stat-do | stat-foreach | stat-for
                    | stat-if | stat-native | stat-return | stat-simple | stat-switch
                    | stat-throw | stat-try | stat-while | stat-variable | stat-expr
                    | stat-comment ;
!stat-block      := '{' stat* '}' ;
!stat-debug      := '#if' 'DEBUG' stat* '#endif' ;
!stat-do         := 'do' stat-block 'while' '(' expr ')' ';' ;
stat-expr        := expr ';' ;
!stat-for        := 'for' '(' var-def? ';' for-cond ';' for-next? ')' stat ;
!stat-foreach    := 'foreach' '(' var-decl 'in' expr ')' stat ;
!stat-if         := 'if' '(' expr ')' stat ('else' stat)? ;
!stat-return     := 'return' (w+ expr)? ';' ;
!stat-switch     := 'switch' '(' expr ')' '{' switch-case* switch-default? '}' ;
!stat-throw      := 'throw' (w+ expr)? ';' ;
!stat-try        := 'try' stat-block try-catch? try-finally? ;
!stat-variable   := ('using' w+)? var ';' (ws* '//' ws* '[' ws* ('!' ws*)? ('*' ws*)?
                    ']' ws* lb)? ;
!stat-while      := 'while' '(' expr ')' stat ;
switch-case      := 'case' w+ expr ':' stat* ;
switch-default   := 'default:' stat* ;
try-catch        := 'catch' '(' type (w+ name-id)? ')' stat-block ;
try-finally      := 'finally' stat-block ;
!type            := type-no-array !> '[]'+ ;
type-generic     := type-name !> '<' (type .. comma) '>' ;
type-no-array    := type-simple | type-generic ;
var              := type w+ name-id ('=' expr)? ;
var-decl         := type w+ name-id ;
var-def          := type w+ name-id '=' expr ;

!expr-literal    := literal ;

literal          := literal-simple | literal-string | literal-char | literal-hex
                    | literal-number ;
!stat-comment    := comment-prefix (comment-tag | ws?) comment-text (ws*
                    comment-line)* ;
type-name        := name ;

comment-tag      := ws* id ':' ws ;
!expr-name       := id ;
!literal-char    := '\'' (escape | ]'\\[) '\'' ;
!literal-string  := '"' (escape | ]"\\[+)* '"' | '@"' ('""' | ]"[+)* '"' ;
name             := 'global::'? (id .. '.') ;
name-id          := id ;
!stat-native     := '#region' ws 'Native' ws '{' guid '}' lb (]\n\r[+ | ~native-end)*
                    native-end lb ;

comment-line     := comment-prefix ws? comment-text ;
escape           := '\\"' | '\\0' | '\\\'' | '\\\\' | '\\b' | '\\f' | '\\n' | '\\r'
                    | '\\t' | '\\u' hex-digit[4] | '\\U' hex-digit[8] ;
!guid            := hex-digit[8] ('-' hex-digit[4])[3] '-' hex-digit[12] ;
!id              := letter id-char* ;
!literal-hex     := @'0x' hex-digit+ @'L'? ;
!literal-simple  := ('null' | 'this' | 'base' | 'true' | 'false') >id-char< ;
!type-simple     := ('bool' | 'sbyte' | 'char' | 'short' | 'int' | 'long' | 'float'
                    | 'double' | 'string' | 'object' | 'void') >id-char< ;

comment-text     := ]\n\r[* lb ;
hex-digit        := dec-digit | 'a'..'f' | 'A'..'F' ;
id-char          := letter | dec-digit ;
!literal-number  := '-'? dec-digit+ ('.' dec-digit+)? (@'E' ('-' | '+')? dec-digit+)?
                    [FLfl]? ;
native-end       := lb ws* '#endregion' ;
w                := ws | lb ;

comma            := ',' ;
comment-prefix   := '//' \ '///' ;
dec-digit        := '0'..'9' ;
expr-add-op      := '+' | '-' ;
expr-assign-op   := '=' | '*=' | '/=' | '%=' | '+=' | '-=' | '<<=' | '>>='
                    | '&=' | '^=' | '|=' ;
expr-equal-op    := '==' | '!=' ;
expr-mul-op      := '*' | '/' \ '//' | '%' ;
expr-relate-op   := '<=' | '<' | '>=' | '>' | 'is' | 'as' ;
expr-shift-op    := '<<' | '>>' ;
lb               := '\r' '\n'? | '\n' ;
letter           := 'a'..'z' | 'A'..'Z' | '_' ;
!stat-simple     := ('break' | 'continue') ';' ;
ws               := '\t' | ' ' ;