mirror of
https://github.com/aptly-dev/aptly.git
synced 2026-05-06 22:18:28 +00:00
Andrey Smirnov
210 lines
10 KiB
BNF
210 lines
10 KiB
BNF
//Copyright 2013 GoGraphviz Authors
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//
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//Licensed under the Apache License, Version 2.0 (the "License");
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//you may not use this file except in compliance with the License.
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//You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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//Unless required by applicable law or agreed to in writing, software
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//distributed under the License is distributed on an "AS IS" BASIS,
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//WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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//See the License for the specific language governing permissions and
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//limitations under the License.
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//This bnf has been derived from http://www.graphviz.org/content/dot-language
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//The rules have been copied and are shown in the comments, with their derived bnf rules below.
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//graph : [ strict ] (graph | digraph) [ ID ] '{' stmt_list '}'
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DotGraph
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: Graph "{" "}" << ast.NewGraph(ast.GRAPH, ast.FALSE, nil, nil) >>
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| Strict Graph "{" "}" << ast.NewGraph(ast.GRAPH, ast.TRUE, nil, nil) >>
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| Graph Id "{" "}" << ast.NewGraph(ast.GRAPH, ast.FALSE, $1, nil) >>
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| Strict Graph Id "{" "}" << ast.NewGraph(ast.GRAPH, ast.TRUE, $2, nil) >>
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| Graph "{" StmtList "}" << ast.NewGraph(ast.GRAPH, ast.FALSE, nil, $2) >>
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| Graph Id "{" StmtList "}" << ast.NewGraph(ast.GRAPH, ast.FALSE, $1, $3) >>
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| Strict Graph "{" StmtList "}" << ast.NewGraph(ast.GRAPH, ast.TRUE, nil, $3) >>
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| Strict Graph Id "{" StmtList "}" << ast.NewGraph(ast.GRAPH, ast.TRUE, $2, $4) >>
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| Digraph "{" "}" << ast.NewGraph(ast.DIGRAPH, ast.FALSE, nil, nil) >>
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| Strict Digraph "{" "}" << ast.NewGraph(ast.DIGRAPH, ast.TRUE, nil, nil) >>
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| Digraph Id "{" "}" << ast.NewGraph(ast.DIGRAPH, ast.FALSE, $1, nil) >>
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| Strict Digraph Id "{" "}" << ast.NewGraph(ast.DIGRAPH, ast.TRUE, $2, nil) >>
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| Digraph "{" StmtList "}" << ast.NewGraph(ast.DIGRAPH, ast.FALSE, nil, $2) >>
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| Digraph Id "{" StmtList "}" << ast.NewGraph(ast.DIGRAPH, ast.FALSE, $1, $3) >>
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| Strict Digraph "{" StmtList "}" << ast.NewGraph(ast.DIGRAPH, ast.TRUE, nil, $3) >>
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| Strict Digraph Id "{" StmtList "}" << ast.NewGraph(ast.DIGRAPH, ast.TRUE, $2, $4) >>
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;
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//stmt_list : [ stmt [ ';' ] [ stmt_list ] ]
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StmtList
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: Stmt1 << ast.NewStmtList($0) >>
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| StmtList Stmt1 << ast.AppendStmtList($0, $1) >>
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;
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Stmt1
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: Stmt << $0, nil >>
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| Stmt ";" << $0, nil >>
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;
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//stmt : node_stmt | edge_stmt | attr_stmt | (ID '=' ID) | subgraph
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Stmt
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: Id "=" Id << ast.NewAttr($0, $2) >>
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| NodeStmt << $0, nil >>
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| EdgeStmt << $0, nil >>
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| AttrStmt << $0, nil >>
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| SubGraphStmt << $0, nil >>
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;
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//attr_stmt : (graph | node | edge) attr_list
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AttrStmt
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: Graph AttrList << ast.NewGraphAttrs($1) >>
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| Node AttrList << ast.NewNodeAttrs($1) >>
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| Edge AttrList << ast.NewEdgeAttrs($1) >>
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;
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//attr_list : '[' [ a_list ] ']' [ attr_list ]
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AttrList
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: "[" "]" << ast.NewAttrList(nil) >>
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| "[" AList "]" << ast.NewAttrList($1) >>
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| AttrList "[" "]" << ast.AppendAttrList($0, nil) >>
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| AttrList "[" AList "]" << ast.AppendAttrList($0, $2) >>
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;
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//a_list : ID [ '=' ID ] [ ',' ] [ a_list ]
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AList
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: Attr << ast.NewAList($0) >>
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| AList Attr << ast.AppendAList($0, $1) >>
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| AList "," Attr << ast.AppendAList($0, $2) >>
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;
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//An a_list clause of the form ID is equivalent to ID=true.
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Attr
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: Id << ast.NewAttr($0, nil) >>
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| Id "=" Id << ast.NewAttr($0, $2) >>
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;
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//edge_stmt : (node_id | subgraph) edgeRHS [ attr_list ]
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EdgeStmt
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: NodeId EdgeRHS << ast.NewEdgeStmt($0, $1, nil) >>
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| NodeId EdgeRHS AttrList << ast.NewEdgeStmt($0, $1, $2) >>
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| SubGraphStmt EdgeRHS << ast.NewEdgeStmt($0, $1, nil) >>
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| SubGraphStmt EdgeRHS AttrList << ast.NewEdgeStmt($0, $1, $2) >>
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;
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//edgeRHS : edgeop (node_id | subgraph) [ edgeRHS ]
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EdgeRHS
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: EdgeOp NodeId << ast.NewEdgeRHS($0, $1) >>
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| EdgeOp SubGraphStmt << ast.NewEdgeRHS($0, $1) >>
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| EdgeRHS EdgeOp NodeId << ast.AppendEdgeRHS($0, $1, $2) >>
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| EdgeRHS EdgeOp SubGraphStmt << ast.AppendEdgeRHS($0, $1, $2) >>
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;
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//node_stmt : node_id [ attr_list ]
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NodeStmt
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: NodeId << ast.NewNodeStmt($0, nil) >>
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| NodeId AttrList << ast.NewNodeStmt($0, $1) >>
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;
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//node_id : ID [ port ]
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NodeId
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: Id << ast.NewNodeId($0, nil) >>
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| Id Port << ast.NewNodeId($0, $1) >>
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;
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//compass_pt : (n | ne | e | se | s | sw | w | nw | c | _)
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//Note also that the allowed compass point values are not keywords,
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//so these strings can be used elsewhere as ordinary identifiers and,
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//conversely, the parser will actually accept any identifier.
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//port : ':' ID [ ':' compass_pt ]
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// | ':' compass_pt
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Port
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: ":" Id << ast.NewPort($1, nil) >>
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| ":" Id ":" Id << ast.NewPort($1, $3) >>
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;
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//subgraph : [ subgraph [ ID ] ] '{' stmt_list '}'
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SubGraphStmt
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: "{" StmtList "}" << ast.NewSubGraph(nil, $1) >>
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| Subgraph "{" StmtList "}" << ast.NewSubGraph(nil, $2) >>
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| Subgraph Id "{" StmtList "}" << ast.NewSubGraph($1, $3) >>
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;
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//An edgeop is -> in directed graphs and -- in undirected graphs.
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EdgeOp
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: "->" << ast.DIRECTED, nil >>
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| "--" << ast.UNDIRECTED, nil >>
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;
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//The keywords node, edge, graph, digraph, subgraph, and strict are case-independent.
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Graph
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: "graph" << $0, nil >>
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| "Graph" << $0, nil >>
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| "GRAPH" << $0, nil >>
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;
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Strict
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: "strict" << $0, nil >>
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| "Strict" << $0, nil >>
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| "STRICT" << $0, nil >>
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;
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Digraph
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: "digraph" << $0, nil >>
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| "Digraph" << $0, nil >>
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| "DiGraph" << $0, nil >>
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| "DIGRAPH" << $0, nil >>
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;
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Node
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: "node" << $0, nil >>
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| "Node" << $0, nil >>
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| "NODE" << $0, nil >>
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;
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Edge
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: "edge" << $0, nil >>
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| "Edge" << $0, nil >>
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| "EDGE" << $0, nil >>
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;
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Subgraph
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: "subgraph" << $0, nil >>
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| "Subgraph" << $0, nil >>
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| "SubGraph" << $0, nil >>
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| "SUBGRAPH" << $0, nil >>
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;
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// An ID is one of the following:
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// Any string of alphabetic ([a-zA-Z'200-'377]) characters, underscores ('_') or digits ([0-9]), not beginning with a digit; //CHECK 200-377
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// a numeral [-]?(.[0-9]+ | [0-9]+(.[0-9]*)? );
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// any double-quoted string ("...") possibly containing escaped quotes ('")1; //TODO
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// an HTML string (<...>).
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// An ID is just a string; the lack of quote characters in the first two forms is just for simplicity.
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// There is no semantic difference between abc_2 and "abc_2", or between 2.34 and "2.34".
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// Obviously, to use a keyword as an ID, it must be quoted. Note that, in HTML strings, angle brackets must occur in matched pairs, and unescaped newlines are allowed.
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// In addition, the content must be legal XML, so that the special XML escape sequences for ", &, <, and > may be necessary in order to embed these characters in attribute values or raw text.
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// Both quoted strings and HTML strings are scanned as a unit, so any embedded comments will be treated as part of the strings.
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Id
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: id << ast.NewId($0) >>
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| string_lit << ast.NewId($0) >>
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| int_lit << ast.NewId($0) >>
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| float_lit << ast.NewId($0) >>
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| html_lit << ast.NewId($0) >>
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;
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//The language supports C++-style comments: /* */ and //.
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//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.
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//TODO (if dot file is not parsable, it might be because of these points)
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//Semicolons aid readability but are not required except in the rare case that a named subgraph with no body immediately preceeds an anonymous subgraph,
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//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.
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//TODO
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//As another aid for readability, dot allows single logical lines to span multiple physical lines using the standard C convention of a backslash immediately preceding a newline character.
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//In addition, double-quoted strings can be concatenated using a '+' operator. As HTML strings can contain newline characters, they do not support the concatenation operator.
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//TODO
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//Note there are still 3 sections on the webpage which have not been included (Subgraphs and Clusters, Lexical and Semantic Notes, and Character Encodings)
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