vendor/rustc-ap-rustc_graphviz/src/lib.rs

   1 //! Generate files suitable for use with [Graphviz](http://www.graphviz.org/)
   2 //!
   3 //! The `render` function generates output (e.g., an `output.dot` file) for
   4 //! use with [Graphviz](http://www.graphviz.org/) by walking a labeled
   5 //! graph. (Graphviz can then automatically lay out the nodes and edges
   6 //! of the graph, and also optionally render the graph as an image or
   7 //! other [output formats](
   8 //! http://www.graphviz.org/content/output-formats), such as SVG.)
   9 //!
  10 //! Rather than impose some particular graph data structure on clients,
  11 //! this library exposes two traits that clients can implement on their
  12 //! own structs before handing them over to the rendering function.
  13 //!
  14 //! Note: This library does not yet provide access to the full
  15 //! expressiveness of the [DOT language](
  16 //! http://www.graphviz.org/doc/info/lang.html). For example, there are
  17 //! many [attributes](http://www.graphviz.org/content/attrs) related to
  18 //! providing layout hints (e.g., left-to-right versus top-down, which
  19 //! algorithm to use, etc). The current intention of this library is to
  20 //! emit a human-readable .dot file with very regular structure suitable
  21 //! for easy post-processing.
  22 //!
  23 //! # Examples
  24 //!
  25 //! The first example uses a very simple graph representation: a list of
  26 //! pairs of ints, representing the edges (the node set is implicit).
  27 //! Each node label is derived directly from the int representing the node,
  28 //! while the edge labels are all empty strings.
  29 //!
  30 //! This example also illustrates how to use `Cow<[T]>` to return
  31 //! an owned vector or a borrowed slice as appropriate: we construct the
  32 //! node vector from scratch, but borrow the edge list (rather than
  33 //! constructing a copy of all the edges from scratch).
  34 //!
  35 //! The output from this example renders five nodes, with the first four
  36 //! forming a diamond-shaped acyclic graph and then pointing to the fifth
  37 //! which is cyclic.
  38 //!
  39 //! ```rust
  40 //! #![feature(rustc_private)]
  41 //!
  42 //! use std::io::Write;
  43 //! use rustc_graphviz as dot;
  44 //!
  45 //! type Nd = isize;
  46 //! type Ed = (isize,isize);
  47 //! struct Edges(Vec<Ed>);
  48 //!
  49 //! pub fn render_to<W: Write>(output: &mut W) {
  50 //!     let edges = Edges(vec![(0,1), (0,2), (1,3), (2,3), (3,4), (4,4)]);
  51 //!     dot::render(&edges, output).unwrap()
  52 //! }
  53 //!
  54 //! impl<'a> dot::Labeller<'a> for Edges {
  55 //!     type Node = Nd;
  56 //!     type Edge = Ed;
  57 //!     fn graph_id(&'a self) -> dot::Id<'a> { dot::Id::new("example1").unwrap() }
  58 //!
  59 //!     fn node_id(&'a self, n: &Nd) -> dot::Id<'a> {
  60 //!         dot::Id::new(format!("N{}", *n)).unwrap()
  61 //!     }
  62 //! }
  63 //!
  64 //! impl<'a> dot::GraphWalk<'a> for Edges {
  65 //!     type Node = Nd;
  66 //!     type Edge = Ed;
  67 //!     fn nodes(&self) -> dot::Nodes<'a,Nd> {
  68 //!         // (assumes that |N| \approxeq |E|)
  69 //!         let &Edges(ref v) = self;
  70 //!         let mut nodes = Vec::with_capacity(v.len());
  71 //!         for &(s,t) in v {
  72 //!             nodes.push(s); nodes.push(t);
  73 //!         }
  74 //!         nodes.sort();
  75 //!         nodes.dedup();
  76 //!         nodes.into()
  77 //!     }
  78 //!
  79 //!     fn edges(&'a self) -> dot::Edges<'a,Ed> {
  80 //!         let &Edges(ref edges) = self;
  81 //!         (&edges[..]).into()
  82 //!     }
  83 //!
  84 //!     fn source(&self, e: &Ed) -> Nd { let &(s,_) = e; s }
  85 //!
  86 //!     fn target(&self, e: &Ed) -> Nd { let &(_,t) = e; t }
  87 //! }
  88 //!
  89 //! # pub fn main() { render_to(&mut Vec::new()) }
  90 //! ```
  91 //!
  92 //! ```no_run
  93 //! # pub fn render_to<W:std::io::Write>(output: &mut W) { unimplemented!() }
  94 //! pub fn main() {
  95 //!     use std::fs::File;
  96 //!     let mut f = File::create("example1.dot").unwrap();
  97 //!     render_to(&mut f)
  98 //! }
  99 //! ```
 100 //!
 101 //! Output from first example (in `example1.dot`):
 102 //!
 103 //! ```dot
 104 //! digraph example1 {
 105 //!     N0[label="N0"];
 106 //!     N1[label="N1"];
 107 //!     N2[label="N2"];
 108 //!     N3[label="N3"];
 109 //!     N4[label="N4"];
 110 //!     N0 -> N1[label=""];
 111 //!     N0 -> N2[label=""];
 112 //!     N1 -> N3[label=""];
 113 //!     N2 -> N3[label=""];
 114 //!     N3 -> N4[label=""];
 115 //!     N4 -> N4[label=""];
 116 //! }
 117 //! ```
 118 //!
 119 //! The second example illustrates using `node_label` and `edge_label` to
 120 //! add labels to the nodes and edges in the rendered graph. The graph
 121 //! here carries both `nodes` (the label text to use for rendering a
 122 //! particular node), and `edges` (again a list of `(source,target)`
 123 //! indices).
 124 //!
 125 //! This example also illustrates how to use a type (in this case the edge
 126 //! type) that shares substructure with the graph: the edge type here is a
 127 //! direct reference to the `(source,target)` pair stored in the graph's
 128 //! internal vector (rather than passing around a copy of the pair
 129 //! itself). Note that this implies that `fn edges(&'a self)` must
 130 //! construct a fresh `Vec<&'a (usize,usize)>` from the `Vec<(usize,usize)>`
 131 //! edges stored in `self`.
 132 //!
 133 //! Since both the set of nodes and the set of edges are always
 134 //! constructed from scratch via iterators, we use the `collect()` method
 135 //! from the `Iterator` trait to collect the nodes and edges into freshly
 136 //! constructed growable `Vec` values (rather than using `Cow` as in the
 137 //! first example above).
 138 //!
 139 //! The output from this example renders four nodes that make up the
 140 //! Hasse-diagram for the subsets of the set `{x, y}`. Each edge is
 141 //! labeled with the &sube; character (specified using the HTML character
 142 //! entity `&sube`).
 143 //!
 144 //! ```rust
 145 //! #![feature(rustc_private)]
 146 //!
 147 //! use std::io::Write;
 148 //! use rustc_graphviz as dot;
 149 //!
 150 //! type Nd = usize;
 151 //! type Ed<'a> = &'a (usize, usize);
 152 //! struct Graph { nodes: Vec<&'static str>, edges: Vec<(usize,usize)> }
 153 //!
 154 //! pub fn render_to<W: Write>(output: &mut W) {
 155 //!     let nodes = vec!["{x,y}","{x}","{y}","{}"];
 156 //!     let edges = vec![(0,1), (0,2), (1,3), (2,3)];
 157 //!     let graph = Graph { nodes: nodes, edges: edges };
 158 //!
 159 //!     dot::render(&graph, output).unwrap()
 160 //! }
 161 //!
 162 //! impl<'a> dot::Labeller<'a> for Graph {
 163 //!     type Node = Nd;
 164 //!     type Edge = Ed<'a>;
 165 //!     fn graph_id(&'a self) -> dot::Id<'a> { dot::Id::new("example2").unwrap() }
 166 //!     fn node_id(&'a self, n: &Nd) -> dot::Id<'a> {
 167 //!         dot::Id::new(format!("N{}", n)).unwrap()
 168 //!     }
 169 //!     fn node_label<'b>(&'b self, n: &Nd) -> dot::LabelText<'b> {
 170 //!         dot::LabelText::LabelStr(self.nodes[*n].into())
 171 //!     }
 172 //!     fn edge_label<'b>(&'b self, _: &Ed) -> dot::LabelText<'b> {
 173 //!         dot::LabelText::LabelStr("&sube;".into())
 174 //!     }
 175 //! }
 176 //!
 177 //! impl<'a> dot::GraphWalk<'a> for Graph {
 178 //!     type Node = Nd;
 179 //!     type Edge = Ed<'a>;
 180 //!     fn nodes(&self) -> dot::Nodes<'a,Nd> { (0..self.nodes.len()).collect() }
 181 //!     fn edges(&'a self) -> dot::Edges<'a,Ed<'a>> { self.edges.iter().collect() }
 182 //!     fn source(&self, e: &Ed) -> Nd { let & &(s,_) = e; s }
 183 //!     fn target(&self, e: &Ed) -> Nd { let & &(_,t) = e; t }
 184 //! }
 185 //!
 186 //! # pub fn main() { render_to(&mut Vec::new()) }
 187 //! ```
 188 //!
 189 //! ```no_run
 190 //! # pub fn render_to<W:std::io::Write>(output: &mut W) { unimplemented!() }
 191 //! pub fn main() {
 192 //!     use std::fs::File;
 193 //!     let mut f = File::create("example2.dot").unwrap();
 194 //!     render_to(&mut f)
 195 //! }
 196 //! ```
 197 //!
 198 //! The third example is similar to the second, except now each node and
 199 //! edge now carries a reference to the string label for each node as well
 200 //! as that node's index. (This is another illustration of how to share
 201 //! structure with the graph itself, and why one might want to do so.)
 202 //!
 203 //! The output from this example is the same as the second example: the
 204 //! Hasse-diagram for the subsets of the set `{x, y}`.
 205 //!
 206 //! ```rust
 207 //! #![feature(rustc_private)]
 208 //!
 209 //! use std::io::Write;
 210 //! use rustc_graphviz as dot;
 211 //!
 212 //! type Nd<'a> = (usize, &'a str);
 213 //! type Ed<'a> = (Nd<'a>, Nd<'a>);
 214 //! struct Graph { nodes: Vec<&'static str>, edges: Vec<(usize,usize)> }
 215 //!
 216 //! pub fn render_to<W: Write>(output: &mut W) {
 217 //!     let nodes = vec!["{x,y}","{x}","{y}","{}"];
 218 //!     let edges = vec![(0,1), (0,2), (1,3), (2,3)];
 219 //!     let graph = Graph { nodes: nodes, edges: edges };
 220 //!
 221 //!     dot::render(&graph, output).unwrap()
 222 //! }
 223 //!
 224 //! impl<'a> dot::Labeller<'a> for Graph {
 225 //!     type Node = Nd<'a>;
 226 //!     type Edge = Ed<'a>;
 227 //!     fn graph_id(&'a self) -> dot::Id<'a> { dot::Id::new("example3").unwrap() }
 228 //!     fn node_id(&'a self, n: &Nd<'a>) -> dot::Id<'a> {
 229 //!         dot::Id::new(format!("N{}", n.0)).unwrap()
 230 //!     }
 231 //!     fn node_label<'b>(&'b self, n: &Nd<'b>) -> dot::LabelText<'b> {
 232 //!         let &(i, _) = n;
 233 //!         dot::LabelText::LabelStr(self.nodes[i].into())
 234 //!     }
 235 //!     fn edge_label<'b>(&'b self, _: &Ed<'b>) -> dot::LabelText<'b> {
 236 //!         dot::LabelText::LabelStr("&sube;".into())
 237 //!     }
 238 //! }
 239 //!
 240 //! impl<'a> dot::GraphWalk<'a> for Graph {
 241 //!     type Node = Nd<'a>;
 242 //!     type Edge = Ed<'a>;
 243 //!     fn nodes(&'a self) -> dot::Nodes<'a,Nd<'a>> {
 244 //!         self.nodes.iter().map(|s| &s[..]).enumerate().collect()
 245 //!     }
 246 //!     fn edges(&'a self) -> dot::Edges<'a,Ed<'a>> {
 247 //!         self.edges.iter()
 248 //!             .map(|&(i,j)|((i, &self.nodes[i][..]),
 249 //!                           (j, &self.nodes[j][..])))
 250 //!             .collect()
 251 //!     }
 252 //!     fn source(&self, e: &Ed<'a>) -> Nd<'a> { let &(s,_) = e; s }
 253 //!     fn target(&self, e: &Ed<'a>) -> Nd<'a> { let &(_,t) = e; t }
 254 //! }
 255 //!
 256 //! # pub fn main() { render_to(&mut Vec::new()) }
 257 //! ```
 258 //!
 259 //! ```no_run
 260 //! # pub fn render_to<W:std::io::Write>(output: &mut W) { unimplemented!() }
 261 //! pub fn main() {
 262 //!     use std::fs::File;
 263 //!     let mut f = File::create("example3.dot").unwrap();
 264 //!     render_to(&mut f)
 265 //! }
 266 //! ```
 267 //!
 268 //! # References
 269 //!
 270 //! * [Graphviz](http://www.graphviz.org/)
 271 //!
 272 //! * [DOT language](http://www.graphviz.org/doc/info/lang.html)
 273
 274 #![doc(
 275     html_root_url = "https://doc.rust-lang.org/nightly/nightly-rustc/",
 276     test(attr(allow(unused_variables), deny(warnings)))
 277 )]
 278 #![feature(nll)]
 279
 280 use LabelText::*;
 281
 282 use std::borrow::Cow;
 283 use std::io;
 284 use std::io::prelude::*;
 285
 286 /// The text for a graphviz label on a node or edge.
 287 pub enum LabelText<'a> {
 288     /// This kind of label preserves the text directly as is.
 289     ///
 290     /// Occurrences of backslashes (`\`) are escaped, and thus appear
 291     /// as backslashes in the rendered label.
 292     LabelStr(Cow<'a, str>),
 293
 294     /// This kind of label uses the graphviz label escString type:
 295     /// <http://www.graphviz.org/content/attrs#kescString>
 296     ///
 297     /// Occurrences of backslashes (`\`) are not escaped; instead they
 298     /// are interpreted as initiating an escString escape sequence.
 299     ///
 300     /// Escape sequences of particular interest: in addition to `\n`
 301     /// to break a line (centering the line preceding the `\n`), there
 302     /// are also the escape sequences `\l` which left-justifies the
 303     /// preceding line and `\r` which right-justifies it.
 304     EscStr(Cow<'a, str>),
 305
 306     /// This uses a graphviz [HTML string label][html]. The string is
 307     /// printed exactly as given, but between `<` and `>`. **No
 308     /// escaping is performed.**
 309     ///
 310     /// [html]: http://www.graphviz.org/content/node-shapes#html
 311     HtmlStr(Cow<'a, str>),
 312 }
 313
 314 /// The style for a node or edge.
 315 /// See <http://www.graphviz.org/doc/info/attrs.html#k:style> for descriptions.
 316 /// Note that some of these are not valid for edges.
 317 #[derive(Copy, Clone, PartialEq, Eq, Debug)]
 318 pub enum Style {
 319     None,
 320     Solid,
 321     Dashed,
 322     Dotted,
 323     Bold,
 324     Rounded,
 325     Diagonals,
 326     Filled,
 327     Striped,
 328     Wedged,
 329 }
 330
 331 impl Style {
 332     pub fn as_slice(self) -> &'static str {
 333         match self {
 334             Style::None => "",
 335             Style::Solid => "solid",
 336             Style::Dashed => "dashed",
 337             Style::Dotted => "dotted",
 338             Style::Bold => "bold",
 339             Style::Rounded => "rounded",
 340             Style::Diagonals => "diagonals",
 341             Style::Filled => "filled",
 342             Style::Striped => "striped",
 343             Style::Wedged => "wedged",
 344         }
 345     }
 346 }
 347
 348 // There is a tension in the design of the labelling API.
 349 //
 350 // For example, I considered making a `Labeller<T>` trait that
 351 // provides labels for `T`, and then making the graph type `G`
 352 // implement `Labeller<Node>` and `Labeller<Edge>`. However, this is
 353 // not possible without functional dependencies. (One could work
 354 // around that, but I did not explore that avenue heavily.)
 355 //
 356 // Another approach that I actually used for a while was to make a
 357 // `Label<Context>` trait that is implemented by the client-specific
 358 // Node and Edge types (as well as an implementation on Graph itself
 359 // for the overall name for the graph). The main disadvantage of this
 360 // second approach (compared to having the `G` type parameter
 361 // implement a Labelling service) that I have encountered is that it
 362 // makes it impossible to use types outside of the current crate
 363 // directly as Nodes/Edges; you need to wrap them in newtype'd
 364 // structs. See e.g., the `No` and `Ed` structs in the examples. (In
 365 // practice clients using a graph in some other crate would need to
 366 // provide some sort of adapter shim over the graph anyway to
 367 // interface with this library).
 368 //
 369 // Another approach would be to make a single `Labeller<N,E>` trait
 370 // that provides three methods (graph_label, node_label, edge_label),
 371 // and then make `G` implement `Labeller<N,E>`. At first this did not
 372 // appeal to me, since I had thought I would need separate methods on
 373 // each data variant for dot-internal identifiers versus user-visible
 374 // labels. However, the identifier/label distinction only arises for
 375 // nodes; graphs themselves only have identifiers, and edges only have
 376 // labels.
 377 //
 378 // So in the end I decided to use the third approach described above.
 379
 380 /// `Id` is a Graphviz `ID`.
 381 pub struct Id<'a> {
 382     name: Cow<'a, str>,
 383 }
 384
 385 impl<'a> Id<'a> {
 386     /// Creates an `Id` named `name`.
 387     ///
 388     /// The caller must ensure that the input conforms to an
 389     /// identifier format: it must be a non-empty string made up of
 390     /// alphanumeric or underscore characters, not beginning with a
 391     /// digit (i.e., the regular expression `[a-zA-Z_][a-zA-Z_0-9]*`).
 392     ///
 393     /// (Note: this format is a strict subset of the `ID` format
 394     /// defined by the DOT language. This function may change in the
 395     /// future to accept a broader subset, or the entirety, of DOT's
 396     /// `ID` format.)
 397     ///
 398     /// Passing an invalid string (containing spaces, brackets,
 399     /// quotes, ...) will return an empty `Err` value.
 400     pub fn new<Name: Into<Cow<'a, str>>>(name: Name) -> Result<Id<'a>, ()> {
 401         let name = name.into();
 402         match name.chars().next() {
 403             Some(c) if c.is_ascii_alphabetic() || c == '_' => {}
 404             _ => return Err(()),
 405         }
 406         if !name.chars().all(|c| c.is_ascii_alphanumeric() || c == '_') {
 407             return Err(());
 408         }
 409
 410         Ok(Id { name })
 411     }
 412
 413     pub fn as_slice(&'a self) -> &'a str {
 414         &*self.name
 415     }
 416
 417     pub fn name(self) -> Cow<'a, str> {
 418         self.name
 419     }
 420 }
 421
 422 /// Each instance of a type that implements `Label<C>` maps to a
 423 /// unique identifier with respect to `C`, which is used to identify
 424 /// it in the generated .dot file. They can also provide more
 425 /// elaborate (and non-unique) label text that is used in the graphviz
 426 /// rendered output.
 427
 428 /// The graph instance is responsible for providing the DOT compatible
 429 /// identifiers for the nodes and (optionally) rendered labels for the nodes and
 430 /// edges, as well as an identifier for the graph itself.
 431 pub trait Labeller<'a> {
 432     type Node;
 433     type Edge;
 434
 435     /// Must return a DOT compatible identifier naming the graph.
 436     fn graph_id(&'a self) -> Id<'a>;
 437
 438     /// Maps `n` to a unique identifier with respect to `self`. The
 439     /// implementor is responsible for ensuring that the returned name
 440     /// is a valid DOT identifier.
 441     fn node_id(&'a self, n: &Self::Node) -> Id<'a>;
 442
 443     /// Maps `n` to one of the [graphviz `shape` names][1]. If `None`
 444     /// is returned, no `shape` attribute is specified.
 445     ///
 446     /// [1]: http://www.graphviz.org/content/node-shapes
 447     fn node_shape(&'a self, _node: &Self::Node) -> Option<LabelText<'a>> {
 448         None
 449     }
 450
 451     /// Maps `n` to a label that will be used in the rendered output.
 452     /// The label need not be unique, and may be the empty string; the
 453     /// default is just the output from `node_id`.
 454     fn node_label(&'a self, n: &Self::Node) -> LabelText<'a> {
 455         LabelStr(self.node_id(n).name)
 456     }
 457
 458     /// Maps `e` to a label that will be used in the rendered output.
 459     /// The label need not be unique, and may be the empty string; the
 460     /// default is in fact the empty string.
 461     fn edge_label(&'a self, _e: &Self::Edge) -> LabelText<'a> {
 462         LabelStr("".into())
 463     }
 464
 465     /// Maps `n` to a style that will be used in the rendered output.
 466     fn node_style(&'a self, _n: &Self::Node) -> Style {
 467         Style::None
 468     }
 469
 470     /// Maps `e` to a style that will be used in the rendered output.
 471     fn edge_style(&'a self, _e: &Self::Edge) -> Style {
 472         Style::None
 473     }
 474 }
 475
 476 /// Escape tags in such a way that it is suitable for inclusion in a
 477 /// Graphviz HTML label.
 478 pub fn escape_html(s: &str) -> String {
 479     s.replace("&", "&amp;").replace("\"", "&quot;").replace("<", "&lt;").replace(">", "&gt;")
 480 }
 481
 482 impl<'a> LabelText<'a> {
 483     pub fn label<S: Into<Cow<'a, str>>>(s: S) -> LabelText<'a> {
 484         LabelStr(s.into())
 485     }
 486
 487     pub fn escaped<S: Into<Cow<'a, str>>>(s: S) -> LabelText<'a> {
 488         EscStr(s.into())
 489     }
 490
 491     pub fn html<S: Into<Cow<'a, str>>>(s: S) -> LabelText<'a> {
 492         HtmlStr(s.into())
 493     }
 494
 495     fn escape_char<F>(c: char, mut f: F)
 496     where
 497         F: FnMut(char),
 498     {
 499         match c {
 500             // not escaping \\, since Graphviz escString needs to
 501             // interpret backslashes; see EscStr above.
 502             '\\' => f(c),
 503             _ => {
 504                 for c in c.escape_default() {
 505                     f(c)
 506                 }
 507             }
 508         }
 509     }
 510     fn escape_str(s: &str) -> String {
 511         let mut out = String::with_capacity(s.len());
 512         for c in s.chars() {
 513             LabelText::escape_char(c, |c| out.push(c));
 514         }
 515         out
 516     }
 517
 518     /// Renders text as string suitable for a label in a .dot file.
 519     /// This includes quotes or suitable delimiters.
 520     pub fn to_dot_string(&self) -> String {
 521         match *self {
 522             LabelStr(ref s) => format!("\"{}\"", s.escape_default()),
 523             EscStr(ref s) => format!("\"{}\"", LabelText::escape_str(&s)),
 524             HtmlStr(ref s) => format!("<{}>", s),
 525         }
 526     }
 527
 528     /// Decomposes content into string suitable for making EscStr that
 529     /// yields same content as self. The result obeys the law
 530     /// render(`lt`) == render(`EscStr(lt.pre_escaped_content())`) for
 531     /// all `lt: LabelText`.
 532     fn pre_escaped_content(self) -> Cow<'a, str> {
 533         match self {
 534             EscStr(s) => s,
 535             LabelStr(s) => {
 536                 if s.contains('\\') {
 537                     (&*s).escape_default().to_string().into()
 538                 } else {
 539                     s
 540                 }
 541             }
 542             HtmlStr(s) => s,
 543         }
 544     }
 545
 546     /// Puts `prefix` on a line above this label, with a blank line separator.
 547     pub fn prefix_line(self, prefix: LabelText<'_>) -> LabelText<'static> {
 548         prefix.suffix_line(self)
 549     }
 550
 551     /// Puts `suffix` on a line below this label, with a blank line separator.
 552     pub fn suffix_line(self, suffix: LabelText<'_>) -> LabelText<'static> {
 553         let mut prefix = self.pre_escaped_content().into_owned();
 554         let suffix = suffix.pre_escaped_content();
 555         prefix.push_str(r"\n\n");
 556         prefix.push_str(&suffix);
 557         EscStr(prefix.into())
 558     }
 559 }
 560
 561 pub type Nodes<'a, N> = Cow<'a, [N]>;
 562 pub type Edges<'a, E> = Cow<'a, [E]>;
 563
 564 // (The type parameters in GraphWalk should be associated items,
 565 // when/if Rust supports such.)
 566
 567 /// GraphWalk is an abstraction over a directed graph = (nodes,edges)
 568 /// made up of node handles `N` and edge handles `E`, where each `E`
 569 /// can be mapped to its source and target nodes.
 570 ///
 571 /// The lifetime parameter `'a` is exposed in this trait (rather than
 572 /// introduced as a generic parameter on each method declaration) so
 573 /// that a client impl can choose `N` and `E` that have substructure
 574 /// that is bound by the self lifetime `'a`.
 575 ///
 576 /// The `nodes` and `edges` method each return instantiations of
 577 /// `Cow<[T]>` to leave implementors the freedom to create
 578 /// entirely new vectors or to pass back slices into internally owned
 579 /// vectors.
 580 pub trait GraphWalk<'a> {
 581     type Node: Clone;
 582     type Edge: Clone;
 583
 584     /// Returns all the nodes in this graph.
 585     fn nodes(&'a self) -> Nodes<'a, Self::Node>;
 586     /// Returns all of the edges in this graph.
 587     fn edges(&'a self) -> Edges<'a, Self::Edge>;
 588     /// The source node for `edge`.
 589     fn source(&'a self, edge: &Self::Edge) -> Self::Node;
 590     /// The target node for `edge`.
 591     fn target(&'a self, edge: &Self::Edge) -> Self::Node;
 592 }
 593
 594 #[derive(Clone, PartialEq, Eq, Debug)]
 595 pub enum RenderOption {
 596     NoEdgeLabels,
 597     NoNodeLabels,
 598     NoEdgeStyles,
 599     NoNodeStyles,
 600
 601     Fontname(String),
 602     DarkTheme,
 603 }
 604
 605 /// Returns vec holding all the default render options.
 606 pub fn default_options() -> Vec<RenderOption> {
 607     vec![]
 608 }
 609
 610 /// Renders directed graph `g` into the writer `w` in DOT syntax.
 611 /// (Simple wrapper around `render_opts` that passes a default set of options.)
 612 pub fn render<'a, N, E, G, W>(g: &'a G, w: &mut W) -> io::Result<()>
 613 where
 614     N: Clone + 'a,
 615     E: Clone + 'a,
 616     G: Labeller<'a, Node = N, Edge = E> + GraphWalk<'a, Node = N, Edge = E>,
 617     W: Write,
 618 {
 619     render_opts(g, w, &[])
 620 }
 621
 622 /// Renders directed graph `g` into the writer `w` in DOT syntax.
 623 /// (Main entry point for the library.)
 624 pub fn render_opts<'a, N, E, G, W>(g: &'a G, w: &mut W, options: &[RenderOption]) -> io::Result<()>
 625 where
 626     N: Clone + 'a,
 627     E: Clone + 'a,
 628     G: Labeller<'a, Node = N, Edge = E> + GraphWalk<'a, Node = N, Edge = E>,
 629     W: Write,
 630 {
 631     writeln!(w, "digraph {} {{", g.graph_id().as_slice())?;
 632
 633     // Global graph properties
 634     let mut graph_attrs = Vec::new();
 635     let mut content_attrs = Vec::new();
 636     let font;
 637     if let Some(fontname) = options.iter().find_map(|option| {
 638         if let RenderOption::Fontname(fontname) = option { Some(fontname) } else { None }
 639     }) {
 640         font = format!(r#"fontname="{}""#, fontname);
 641         graph_attrs.push(&font[..]);
 642         content_attrs.push(&font[..]);
 643     }
 644     if options.contains(&RenderOption::DarkTheme) {
 645         graph_attrs.push(r#"bgcolor="black""#);
 646         graph_attrs.push(r#"fontcolor="white""#);
 647         content_attrs.push(r#"color="white""#);
 648         content_attrs.push(r#"fontcolor="white""#);
 649     }
 650     if !(graph_attrs.is_empty() && content_attrs.is_empty()) {
 651         writeln!(w, r#"    graph[{}];"#, graph_attrs.join(" "))?;
 652         let content_attrs_str = content_attrs.join(" ");
 653         writeln!(w, r#"    node[{}];"#, content_attrs_str)?;
 654         writeln!(w, r#"    edge[{}];"#, content_attrs_str)?;
 655     }
 656
 657     let mut text = Vec::new();
 658     for n in g.nodes().iter() {
 659         write!(w, "    ")?;
 660         let id = g.node_id(n);
 661
 662         let escaped = &g.node_label(n).to_dot_string();
 663
 664         write!(text, "{}", id.as_slice()).unwrap();
 665
 666         if !options.contains(&RenderOption::NoNodeLabels) {
 667             write!(text, "[label={}]", escaped).unwrap();
 668         }
 669
 670         let style = g.node_style(n);
 671         if !options.contains(&RenderOption::NoNodeStyles) && style != Style::None {
 672             write!(text, "[style=\"{}\"]", style.as_slice()).unwrap();
 673         }
 674
 675         if let Some(s) = g.node_shape(n) {
 676             write!(text, "[shape={}]", &s.to_dot_string()).unwrap();
 677         }
 678
 679         writeln!(text, ";").unwrap();
 680         w.write_all(&text[..])?;
 681
 682         text.clear();
 683     }
 684
 685     for e in g.edges().iter() {
 686         let escaped_label = &g.edge_label(e).to_dot_string();
 687         write!(w, "    ")?;
 688         let source = g.source(e);
 689         let target = g.target(e);
 690         let source_id = g.node_id(&source);
 691         let target_id = g.node_id(&target);
 692
 693         write!(text, "{} -> {}", source_id.as_slice(), target_id.as_slice()).unwrap();
 694
 695         if !options.contains(&RenderOption::NoEdgeLabels) {
 696             write!(text, "[label={}]", escaped_label).unwrap();
 697         }
 698
 699         let style = g.edge_style(e);
 700         if !options.contains(&RenderOption::NoEdgeStyles) && style != Style::None {
 701             write!(text, "[style=\"{}\"]", style.as_slice()).unwrap();
 702         }
 703
 704         writeln!(text, ";").unwrap();
 705         w.write_all(&text[..])?;
 706
 707         text.clear();
 708     }
 709
 710     writeln!(w, "}}")
 711 }
 712
 713 #[cfg(test)]
 714 mod tests;