aud.example.graph.GraphParser Class Reference

Parse text to build graph. More...

Collaboration diagram for aud.example.graph.GraphParser:

Public Member Functions
	GraphParser (AbstractGraph< AbstractNode, AbstractEdge > g)
	create new parser for graph g More...
void	parse (String input)
	parse input More...
void	parse (File file)
	parse(String) contents of file More...
void	setVerbose (boolean b)
	set verbose mode (report state to System.err) More...

Static Public Member Functions
static void	main (String[] args)
	test and example for usage More...

Protected Member Functions
String	errorNear ()
	helper: generate a simple error message More...
int	lookahead ()
	helper: "lookahead" is the usual phrasing More...
void	nextToken ()
	helper: consume current token and advance to next token More...
void	expect (int tokenid, String text)
	helper: check token (without calling nextToken!) More...
void	verbose (int level, String message)
	helper: print out information More...
void	graph (int level)
	parse list of nodes/edges More...
AbstractEdge	edge (int level)
	parse edge More...
AbstractNode	node (int level)
	parse node More...
double[]	pos (int level)
	parse position More...
Double	weight (int level)
	parse weight More...

Detailed Description

Parse text to build graph.

 graph  ::= edges
 edges  ::= edge | edges edge
 edge   ::= ( node | node ( '--' | '->' ) weight node )
 node   ::= IDENTIFIER | IDENTIFIER pos
 pos    ::= '@' '(' NUMBER ',' NUMBER ')'
 weight ::= NIL | '(' NUMBER ')'

See also

Tokenizer

aud.graph.AbstractGraph

Definition at line 23 of file GraphParser.java.

Constructor & Destructor Documentation

GraphParser()

aud.example.graph.GraphParser.GraphParser

(

AbstractGraph< AbstractNode, AbstractEdge >

g

)

create new parser for graph g

Definition at line 31 of file GraphParser.java.

                                                                 {
    graph_=g;
  }

Member Function Documentation

edge()

AbstractEdge aud.example.graph.GraphParser.edge ( int  level )

protected

parse edge

Definition at line 107 of file GraphParser.java.

                                         {
    verbose(level,"<edge>");
    AbstractNode from=node(level+1);
    if (lookahead()!=Tokenizer.EDGE && lookahead()!=Tokenizer.DEDGE)
      return null;
 
    boolean directed=(lookahead()==Tokenizer.DEDGE);
 
    if (directed ^ graph_.isDirected())
      throw new RuntimeException("specified directed edge "+
                                 "for undirected graph or vice versa");
 
    nextToken();
 
    Double w=weight(level+1);
 
    AbstractNode to=node(level+1);
    AbstractEdge e=graph_.addEdge(from,to);
 
    if (w!=null)
      e.setWeight(w);
 
    return e;
  }

References aud.example.graph.Tokenizer.DEDGE, aud.example.graph.Tokenizer.EDGE, aud.example.graph.GraphParser.lookahead(), aud.example.graph.GraphParser.node(), and aud.example.graph.GraphParser.verbose().

Referenced by aud.example.graph.GraphParser.graph().

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errorNear()

String aud.example.graph.GraphParser.errorNear ( )

protected

helper: generate a simple error message

Definition at line 58 of file GraphParser.java.

                               {
    return "near '"+scanner_.matchedText()+
      "'\nbefore '"+scanner_.remainder()+"'";
  }

expect()

void aud.example.graph.GraphParser.expect ( int  tokenid, String  text  )

protected

helper: check token (without calling nextToken!)

Exceptions

RuntimeException

if token does not match (syntax error)

Definition at line 78 of file GraphParser.java.

                                                 {
    if (lookahead()!=tokenid)
      throw new RuntimeException("expected '"+text+"' got '"+
                            scanner_.matchedText()+"'\nbefore '"+
                            scanner_.remainder());
  }

References aud.example.graph.GraphParser.lookahead().

Referenced by aud.example.graph.GraphParser.node(), aud.example.graph.GraphParser.pos(), and aud.example.graph.GraphParser.weight().

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graph()

void aud.example.graph.GraphParser.graph ( int  level )

protected

parse list of nodes/edges

Definition at line 99 of file GraphParser.java.

                                  {
    verbose(level,"<graph>");
 
    while (lookahead()!=Tokenizer.END_OF_INPUT)
      edge(level+1);
  }

References aud.example.graph.GraphParser.edge(), aud.util.LexicalScanner.END_OF_INPUT, aud.example.graph.GraphParser.lookahead(), and aud.example.graph.GraphParser.verbose().

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lookahead()

int aud.example.graph.GraphParser.lookahead ( )

protected

helper: "lookahead" is the usual phrasing

Definition at line 64 of file GraphParser.java.

                            {
    return scanner_.matchedTokenId();
  }

Referenced by aud.example.graph.GraphParser.edge(), aud.example.graph.GraphParser.expect(), aud.example.graph.GraphParser.graph(), aud.example.graph.GraphParser.node(), and aud.example.graph.GraphParser.weight().

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main()

static void aud.example.graph.GraphParser.main ( String[]  args )

static

test and example for usage

Definition at line 205 of file GraphParser.java.

                                         {
 
    GraphAM<SimpleNode,SimpleEdge> g=
      new GraphAM<SimpleNode,SimpleEdge>
      (new SimpleNode(),new SimpleEdge(),false);
 
    String input=(args.length>0) ?
        Sys.readFile(new File(args[0])) : "a@(1,1) -- [1] b b -- c c -- a";
 
    System.out.println("input = '"+input+"'");
 
    GraphParser p=
      new GraphParser((AbstractGraph<AbstractNode,AbstractEdge>) (Object) g);
    p.setVerbose(true);
    p.parse(input);
 
    System.out.println(g);
    System.out.println(g.toDot());
 
    DotViewer.displayWindow(g,"graph").setExitOnClose();
  }

References aud.util.DotViewer.displayWindow(), aud.example.graph.GraphParser.parse(), aud.util.Sys.readFile(), aud.util.DotViewer.setExitOnClose(), aud.example.graph.GraphParser.setVerbose(), and aud.graph.AbstractGraph< Node extends AbstractNode, Edge extends AbstractEdge >.toDot().

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nextToken()

void aud.example.graph.GraphParser.nextToken ( )

protected

helper: consume current token and advance to next token

Definition at line 69 of file GraphParser.java.

                             {
    if (scanner_.next()==Tokenizer.NO_MATCH)
      throw new RuntimeException("unknown token: lexcial analysis failed at '"+
                            scanner_.remainder()+"'");
  }

Referenced by aud.example.graph.GraphParser.pos(), and aud.example.graph.GraphParser.weight().

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node()

AbstractNode aud.example.graph.GraphParser.node ( int  level )

protected

parse node

Definition at line 133 of file GraphParser.java.

                                         {
    verbose(level,"<node>");
    if (lookahead()!=Tokenizer.IDENTIFIER &&
        lookahead()!=Tokenizer.NUMBER)
      expect(Tokenizer.IDENTIFIER,"node identifier");
    String id=scanner_.matchedText();
    nextToken();
 
    AbstractNode n=nodeMap_.find(id);
 
    if (n==null) {
      n=graph_.addNode();
      n.setLabel(id);
      nodeMap_.insert(id,n);
    }
 
    if (lookahead()==Tokenizer.AT) {
      double[] p=pos(level+1);
      n.setPosition(p[0],p[1]);
    }
 
    return n;
  }

References aud.example.graph.GraphParser.expect(), aud.example.graph.Tokenizer.IDENTIFIER, aud.example.graph.GraphParser.lookahead(), aud.example.graph.Tokenizer.NUMBER, and aud.example.graph.GraphParser.verbose().

Referenced by aud.example.graph.GraphParser.edge().

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parse() [1/2]

void aud.example.graph.GraphParser.parse

(

File

file

)

parse(String) contents of file

Definition at line 48 of file GraphParser.java.

                               {
    parse(Sys.readFile(file));
  }

References aud.example.graph.GraphParser.parse(), and aud.util.Sys.readFile().

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parse() [2/2]

void aud.example.graph.GraphParser.parse

(

String

input

)

parse input

Parameters

input

text representation of parser

Exceptions

RuntimeException

on syntax error or invalid operation

Definition at line 39 of file GraphParser.java.

                                  {
    scanner_ = new Tokenizer(input);
    scanner_.next(); // use as "lookahead"
    nodeMap_=new HashMap<String,AbstractNode>();
    graph(0);
    expect(Tokenizer.END_OF_INPUT,"<end of input>");
  }

Referenced by aud.example.graph.GraphParser.main(), aud.example.graph.RetroMaze.main(), aud.example.graph.TraversalExample.main(), aud.example.graph.MyGraph.MyGraph(), and aud.example.graph.GraphParser.parse().

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pos()

double[] aud.example.graph.GraphParser.pos ( int  level )

protected

parse position

Definition at line 158 of file GraphParser.java.

                                    {
    verbose(level,"<pos>");
    expect(Tokenizer.AT,"@(x,y)");
    nextToken();
    expect(Tokenizer.LEFT_PAREN,"'(' position");
    nextToken();
 
    double x,y;
    expect(Tokenizer.NUMBER,"position x-coordinate");
    x=Double.parseDouble(scanner_.matchedText());
    nextToken();
 
    expect(Tokenizer.COMMA,"',' comma separating coordinates");
    nextToken();
 
    expect(Tokenizer.NUMBER,"position y-coordinate");
    y=Double.parseDouble(scanner_.matchedText());
    nextToken();
 
    expect(Tokenizer.RIGHT_PAREN,"')' position");
    nextToken();
 
    return new double[] { x,y };
  }

References aud.example.graph.Tokenizer.AT, aud.example.graph.GraphParser.expect(), aud.example.graph.Tokenizer.LEFT_PAREN, aud.example.graph.GraphParser.nextToken(), aud.example.graph.Tokenizer.NUMBER, and aud.example.graph.GraphParser.verbose().

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setVerbose()

void aud.example.graph.GraphParser.setVerbose

(

boolean

b

)

set verbose mode (report state to System.err)

Definition at line 53 of file GraphParser.java.

                                    {
    verbose_=b;
  }

Referenced by aud.example.graph.GraphParser.main().

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verbose()

void aud.example.graph.GraphParser.verbose ( int  level, String  message  )

protected

helper: print out information

Definition at line 86 of file GraphParser.java.

                                                   {
    if (verbose_) {
      System.err.println(Sys.indent(level)+message+
                         " ['"+scanner_.matchedText()+"','"+
                         scanner_.remainder()+"']");
    }
  }

Referenced by aud.example.graph.GraphParser.edge(), aud.example.graph.GraphParser.graph(), aud.example.graph.GraphParser.node(), aud.example.graph.GraphParser.pos(), and aud.example.graph.GraphParser.weight().

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weight()

Double aud.example.graph.GraphParser.weight ( int  level )

protected

parse weight

Definition at line 184 of file GraphParser.java.

                                     {
    verbose(level,"<weight>");
 
    if (lookahead()!=Tokenizer.LEFT_BRACE)
      return null;
 
    nextToken();
    expect(Tokenizer.NUMBER,"number (weight)");
 
    double w=Double.parseDouble(scanner_.matchedText());
    nextToken();
 
    expect(Tokenizer.RIGHT_BRACE,"')'");
    nextToken();
 
    return w;
  }

References aud.example.graph.GraphParser.expect(), aud.example.graph.Tokenizer.LEFT_BRACE, aud.example.graph.GraphParser.lookahead(), aud.example.graph.GraphParser.nextToken(), aud.example.graph.Tokenizer.NUMBER, and aud.example.graph.GraphParser.verbose().

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The documentation for this class was generated from the following file:

• GraphParser.java