//Copyright 2013 GoGraphviz Authors
//
//Licensed under the Apache License, Version 2.0 (the "License");
//you may not use this file except in compliance with the License.
//You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
//Unless required by applicable law or agreed to in writing, software
//distributed under the License is distributed on an "AS IS" BASIS,
//WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
//See the License for the specific language governing permissions and
//limitations under the License.
//This bnf has been derived from https://graphviz.gitlab.io/_pages/doc/info/lang.html
//The rules have been copied and are shown in the comments, with their derived bnf rules below.
// ### [ Tokens ] ##############################################################
// The keywords node, edge, graph, digraph, subgraph, and strict are case-
// independent.
node
: 'n' 'o' 'd' 'e'
| 'N' 'o' 'd' 'e'
| 'N' 'O' 'D' 'E'
;
edge
: 'e' 'd' 'g' 'e'
| 'E' 'd' 'g' 'e'
| 'E' 'D' 'G' 'E'
;
// TODO: Rename graphx to graph once gocc#20 is fixed [1].
//
// [1]: https://github.com/goccmack/gocc/issues/20
graphx
: 'g' 'r' 'a' 'p' 'h'
| 'G' 'r' 'a' 'p' 'h'
| 'G' 'R' 'A' 'P' 'H'
;
digraph
: 'd' 'i' 'g' 'r' 'a' 'p' 'h'
| 'D' 'i' 'g' 'r' 'a' 'p' 'h'
| 'd' 'i' 'G' 'r' 'a' 'p' 'h'
| 'D' 'i' 'G' 'r' 'a' 'p' 'h'
| 'D' 'I' 'G' 'R' 'A' 'P' 'H'
;
subgraph
: 's' 'u' 'b' 'g' 'r' 'a' 'p' 'h'
| 'S' 'u' 'b' 'g' 'r' 'a' 'p' 'h'
| 's' 'u' 'b' 'G' 'r' 'a' 'p' 'h'
| 'S' 'u' 'b' 'G' 'r' 'a' 'p' 'h'
| 'S' 'U' 'B' 'G' 'R' 'A' 'P' 'H'
;
strict
: 's' 't' 'r' 'i' 'c' 't'
| 'S' 't' 'r' 'i' 'c' 't'
| 'S' 'T' 'R' 'I' 'C' 'T'
;
// An arbitrary ASCII character except null (0x00), double quote (0x22) and
// backslash (0x5C).
_ascii_char
// skip null (0x00)
: '\x01' - '\x21'
// skip double quote (0x22)
| '\x23' - '\x5B'
// skip backslash (0x5C)
| '\x5D' - '\x7F'
;
_ascii_letter
: 'a' - 'z'
| 'A' - 'Z'
;
_ascii_digit : '0' - '9' ;
_unicode_char
: _ascii_char
| _unicode_byte
;
_unicode_byte
: '\u0080' - '\uFFFC'
// skip invalid code point (\uFFFD)
| '\uFFFE' - '\U0010FFFF'
;
_letter : _ascii_letter | _unicode_byte | '_' ;
_decimal_digit : _ascii_digit ;
_decimals : _decimal_digit { _decimal_digit } ;
// An ID is one of the following:
//
// 1) Any string of alphabetic ([a-zA-Z\200-\377]) characters, underscores
// ('_') or digits ([0-9]), not beginning with a digit;
//
// 2) a numeral [-]?(.[0-9]+ | [0-9]+(.[0-9]*)? );
//
// 3) any double-quoted string ("...") possibly containing escaped quotes
// (\");
//
// 4) an HTML string (<...>).
id
: _letter { _letter | _decimal_digit }
| _int_lit
| _string_lit
| _html_lit
;
_int_lit
: [ '-' ] '.' _decimals
| [ '-' ] _decimals [ '.' { _decimal_digit } ]
;
// In quoted strings in DOT, the only escaped character is double-quote (").
// That is, in quoted strings, the dyad \" is converted to "; all other
// characters are left unchanged. In particular, \\ remains \\.
_escaped_char : '\\' ( _unicode_char | '"' | '\\' ) ;
_char : _unicode_char | _escaped_char ;
_string_lit : '"' { _char } '"' ;
// An arbitrary HTML character except null (0x00), left angle bracket (0x3C) and
// right angle bracket (0x3E).
_html_char
// skip null (0x00)
: '\x01' - '\x3B'
// skip left angle bracket (0x3C)
| '\x3D'
// skip right angle bracket (0x3E)
| '\x3F' - '\xFF'
;
_html_chars : { _html_char } ;
_html_tag : '<' _html_chars '>' ;
_html_lit : '<' { _html_chars | _html_tag } '>' ;
// The language supports C++-style comments: /* */ and //. In addition, a line
// beginning with a '#' character is considered a line output from a C
// preprocessor (e.g., # 34 to indicate line 34 ) and discarded.
_line_comment
: '/' '/' { . } '\n'
| '#' { . } '\n'
;
_block_comment : '/' '*' { . | '*' } '*' '/' ;
!comment : _line_comment | _block_comment ;
!whitespace : ' ' | '\t' | '\r' | '\n' ;
// ### [ Syntax ] ##############################################################
<< import "github.com/awalterschulze/gographviz/ast" >>
//graph : [ strict ] (graph | digraph) [ ID ] '{' stmt_list '}'
DotGraph
: graphx "{" "}" << ast.NewGraph(ast.GRAPH, ast.FALSE, nil, nil) >>
| strict graphx "{" "}" << ast.NewGraph(ast.GRAPH, ast.TRUE, nil, nil) >>
| graphx Id "{" "}" << ast.NewGraph(ast.GRAPH, ast.FALSE, $1, nil) >>
| strict graphx Id "{" "}" << ast.NewGraph(ast.GRAPH, ast.TRUE, $2, nil) >>
| graphx "{" StmtList "}" << ast.NewGraph(ast.GRAPH, ast.FALSE, nil, $2) >>
| graphx Id "{" StmtList "}" << ast.NewGraph(ast.GRAPH, ast.FALSE, $1, $3) >>
| strict graphx "{" StmtList "}" << ast.NewGraph(ast.GRAPH, ast.TRUE, nil, $3) >>
| strict graphx Id "{" StmtList "}" << ast.NewGraph(ast.GRAPH, ast.TRUE, $2, $4) >>
| digraph "{" "}" << ast.NewGraph(ast.DIGRAPH, ast.FALSE, nil, nil) >>
| strict digraph "{" "}" << ast.NewGraph(ast.DIGRAPH, ast.TRUE, nil, nil) >>
| digraph Id "{" "}" << ast.NewGraph(ast.DIGRAPH, ast.FALSE, $1, nil) >>
| strict digraph Id "{" "}" << ast.NewGraph(ast.DIGRAPH, ast.TRUE, $2, nil) >>
| digraph "{" StmtList "}" << ast.NewGraph(ast.DIGRAPH, ast.FALSE, nil, $2) >>
| digraph Id "{" StmtList "}" << ast.NewGraph(ast.DIGRAPH, ast.FALSE, $1, $3) >>
| strict digraph "{" StmtList "}" << ast.NewGraph(ast.DIGRAPH, ast.TRUE, nil, $3) >>
| strict digraph Id "{" StmtList "}" << ast.NewGraph(ast.DIGRAPH, ast.TRUE, $2, $4) >>
;
//stmt_list : [ stmt [ ';' ] [ stmt_list ] ]
StmtList
: Stmt1 << ast.NewStmtList($0) >>
| StmtList Stmt1 << ast.AppendStmtList($0, $1) >>
;
Stmt1
: Stmt << $0, nil >>
| Stmt ";" << $0, nil >>
;
//stmt : node_stmt | edge_stmt | attr_stmt | (ID '=' ID) | subgraph
Stmt
: Id "=" Id << ast.NewAttr($0, $2) >>
| NodeStmt << $0, nil >>
| EdgeStmt << $0, nil >>
| AttrStmt << $0, nil >>
| SubGraphStmt << $0, nil >>
;
//attr_stmt : (graph | node | edge) attr_list
AttrStmt
: graphx AttrList << ast.NewGraphAttrs($1) >>
| node AttrList << ast.NewNodeAttrs($1) >>
| edge AttrList << ast.NewEdgeAttrs($1) >>
;
//attr_list : '[' [ a_list ] ']' [ attr_list ]
AttrList
: "[" "]" << ast.NewAttrList(nil) >>
| "[" AList "]" << ast.NewAttrList($1) >>
| AttrList "[" "]" << ast.AppendAttrList($0, nil) >>
| AttrList "[" AList "]" << ast.AppendAttrList($0, $2) >>
;
//a_list : ID [ '=' ID ] [ ',' ] [ a_list ]
AList
: Attr << ast.NewAList($0) >>
| AList Attr << ast.AppendAList($0, $1) >>
| AList "," Attr << ast.AppendAList($0, $2) >>
;
//An a_list clause of the form ID is equivalent to ID=true.
Attr
: Id << ast.NewAttr($0, nil) >>
| Id "=" Id << ast.NewAttr($0, $2) >>
;
//edge_stmt : (node_id | subgraph) edgeRHS [ attr_list ]
EdgeStmt
: NodeId EdgeRHS << ast.NewEdgeStmt($0, $1, nil) >>
| NodeId EdgeRHS AttrList << ast.NewEdgeStmt($0, $1, $2) >>
| SubGraphStmt EdgeRHS << ast.NewEdgeStmt($0, $1, nil) >>
| SubGraphStmt EdgeRHS AttrList << ast.NewEdgeStmt($0, $1, $2) >>
;
//edgeRHS : edgeop (node_id | subgraph) [ edgeRHS ]
EdgeRHS
: EdgeOp NodeId << ast.NewEdgeRHS($0, $1) >>
| EdgeOp SubGraphStmt << ast.NewEdgeRHS($0, $1) >>
| EdgeRHS EdgeOp NodeId << ast.AppendEdgeRHS($0, $1, $2) >>
| EdgeRHS EdgeOp SubGraphStmt << ast.AppendEdgeRHS($0, $1, $2) >>
;
//node_stmt : node_id [ attr_list ]
NodeStmt
: NodeId << ast.NewNodeStmt($0, nil) >>
| NodeId AttrList << ast.NewNodeStmt($0, $1) >>
;
//node_id : ID [ port ]
NodeId
: Id << ast.NewNodeID($0, nil) >>
| Id Port << ast.NewNodeID($0, $1) >>
;
//compass_pt : (n | ne | e | se | s | sw | w | nw | c | _)
//Note also that the allowed compass point values are not keywords,
//so these strings can be used elsewhere as ordinary identifiers and,
//conversely, the parser will actually accept any identifier.
//port : ':' ID [ ':' compass_pt ]
// | ':' compass_pt
Port
: ":" Id << ast.NewPort($1, nil), nil >>
| ":" Id ":" Id << ast.NewPort($1, $3), nil >>
;
//TODO: Semicolons aid readability but are not required except in the rare case that a named subgraph with no body immediately preceeds an anonymous subgraph,
//since the precedence rules cause this sequence to be parsed as a subgraph with a heading and a body. Also, any amount of whitespace may be inserted between terminals.
//subgraph : [ subgraph [ ID ] ] '{' stmt_list '}'
SubGraphStmt
: "{" StmtList "}" << ast.NewSubGraph(nil, $1) >>
| subgraph "{" StmtList "}" << ast.NewSubGraph(nil, $2) >>
| subgraph Id "{" StmtList "}" << ast.NewSubGraph($1, $3) >>
| subgraph "{" "}" << ast.NewSubGraph(nil, nil) >>
| subgraph Id "{" "}" << ast.NewSubGraph($1, nil) >>
;
//An edgeop is -> in directed graphs and -- in undirected graphs.
EdgeOp
: "->" << ast.DIRECTED, nil >>
| "--" << ast.UNDIRECTED, nil >>
;
Id
: id << ast.NewID($0) >>
;