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+//! Generate files suitable for use with [Graphviz](https://www.graphviz.org/)
+//!
+//! The `render` function generates output (e.g., an `output.dot` file) for
+//! use with [Graphviz](https://www.graphviz.org/) by walking a labeled
+//! graph. (Graphviz can then automatically lay out the nodes and edges
+//! of the graph, and also optionally render the graph as an image or
+//! other [output formats](https://www.graphviz.org/docs/outputs), such as SVG.)
+//!
+//! Rather than impose some particular graph data structure on clients,
+//! this library exposes two traits that clients can implement on their
+//! own structs before handing them over to the rendering function.
+//!
+//! Note: This library does not yet provide access to the full
+//! expressiveness of the [DOT language](https://www.graphviz.org/doc/info/lang.html).
+//! For example, there are many [attributes](https://www.graphviz.org/doc/info/attrs.html)
+//! related to providing layout hints (e.g., left-to-right versus top-down, which
+//! algorithm to use, etc). The current intention of this library is to
+//! emit a human-readable .dot file with very regular structure suitable
+//! for easy post-processing.
+//!
+//! # Examples
+//!
+//! The first example uses a very simple graph representation: a list of
+//! pairs of ints, representing the edges (the node set is implicit).
+//! Each node label is derived directly from the int representing the node,
+//! while the edge labels are all empty strings.
+//!
+//! This example also illustrates how to use `Cow<[T]>` to return
+//! an owned vector or a borrowed slice as appropriate: we construct the
+//! node vector from scratch, but borrow the edge list (rather than
+//! constructing a copy of all the edges from scratch).
+//!
+//! The output from this example renders five nodes, with the first four
+//! forming a diamond-shaped acyclic graph and then pointing to the fifth
+//! which is cyclic.
+//!
+//! ```rust
+//! #![feature(rustc_private)]
+//!
+//! use std::io::Write;
+//! use rustc_graphviz as dot;
+//!
+//! type Nd = isize;
+//! type Ed = (isize,isize);
+//! struct Edges(Vec<Ed>);
+//!
+//! pub fn render_to<W: Write>(output: &mut W) {
+//! let edges = Edges(vec![(0,1), (0,2), (1,3), (2,3), (3,4), (4,4)]);
+//! dot::render(&edges, output).unwrap()
+//! }
+//!
+//! impl<'a> dot::Labeller<'a> for Edges {
+//! type Node = Nd;
+//! type Edge = Ed;
+//! fn graph_id(&'a self) -> dot::Id<'a> { dot::Id::new("example1").unwrap() }
+//!
+//! fn node_id(&'a self, n: &Nd) -> dot::Id<'a> {
+//! dot::Id::new(format!("N{}", *n)).unwrap()
+//! }
+//! }
+//!
+//! impl<'a> dot::GraphWalk<'a> for Edges {
+//! type Node = Nd;
+//! type Edge = Ed;
+//! fn nodes(&self) -> dot::Nodes<'a,Nd> {
+//! // (assumes that |N| \approxeq |E|)
+//! let &Edges(ref v) = self;
+//! let mut nodes = Vec::with_capacity(v.len());
+//! for &(s,t) in v {
+//! nodes.push(s); nodes.push(t);
+//! }
+//! nodes.sort();
+//! nodes.dedup();
+//! nodes.into()
+//! }
+//!
+//! fn edges(&'a self) -> dot::Edges<'a,Ed> {
+//! let &Edges(ref edges) = self;
+//! (&edges[..]).into()
+//! }
+//!
+//! fn source(&self, e: &Ed) -> Nd { let &(s,_) = e; s }
+//!
+//! fn target(&self, e: &Ed) -> Nd { let &(_,t) = e; t }
+//! }
+//!
+//! # pub fn main() { render_to(&mut Vec::new()) }
+//! ```
+//!
+//! ```no_run
+//! # pub fn render_to<W:std::io::Write>(output: &mut W) { unimplemented!() }
+//! pub fn main() {
+//! use std::fs::File;
+//! let mut f = File::create("example1.dot").unwrap();
+//! render_to(&mut f)
+//! }
+//! ```
+//!
+//! Output from first example (in `example1.dot`):
+//!
+//! ```dot
+//! digraph example1 {
+//! N0[label="N0"];
+//! N1[label="N1"];
+//! N2[label="N2"];
+//! N3[label="N3"];
+//! N4[label="N4"];
+//! N0 -> N1[label=""];
+//! N0 -> N2[label=""];
+//! N1 -> N3[label=""];
+//! N2 -> N3[label=""];
+//! N3 -> N4[label=""];
+//! N4 -> N4[label=""];
+//! }
+//! ```
+//!
+//! The second example illustrates using `node_label` and `edge_label` to
+//! add labels to the nodes and edges in the rendered graph. The graph
+//! here carries both `nodes` (the label text to use for rendering a
+//! particular node), and `edges` (again a list of `(source,target)`
+//! indices).
+//!
+//! This example also illustrates how to use a type (in this case the edge
+//! type) that shares substructure with the graph: the edge type here is a
+//! direct reference to the `(source,target)` pair stored in the graph's
+//! internal vector (rather than passing around a copy of the pair
+//! itself). Note that this implies that `fn edges(&'a self)` must
+//! construct a fresh `Vec<&'a (usize,usize)>` from the `Vec<(usize,usize)>`
+//! edges stored in `self`.
+//!
+//! Since both the set of nodes and the set of edges are always
+//! constructed from scratch via iterators, we use the `collect()` method
+//! from the `Iterator` trait to collect the nodes and edges into freshly
+//! constructed growable `Vec` values (rather than using `Cow` as in the
+//! first example above).
+//!
+//! The output from this example renders four nodes that make up the
+//! Hasse-diagram for the subsets of the set `{x, y}`. Each edge is
+//! labeled with the &sube; character (specified using the HTML character
+//! entity `&sube`).
+//!
+//! ```rust
+//! #![feature(rustc_private)]
+//!
+//! use std::io::Write;
+//! use rustc_graphviz as dot;
+//!
+//! type Nd = usize;
+//! type Ed<'a> = &'a (usize, usize);
+//! struct Graph { nodes: Vec<&'static str>, edges: Vec<(usize,usize)> }
+//!
+//! pub fn render_to<W: Write>(output: &mut W) {
+//! let nodes = vec!["{x,y}","{x}","{y}","{}"];
+//! let edges = vec![(0,1), (0,2), (1,3), (2,3)];
+//! let graph = Graph { nodes: nodes, edges: edges };
+//!
+//! dot::render(&graph, output).unwrap()
+//! }
+//!
+//! impl<'a> dot::Labeller<'a> for Graph {
+//! type Node = Nd;
+//! type Edge = Ed<'a>;
+//! fn graph_id(&'a self) -> dot::Id<'a> { dot::Id::new("example2").unwrap() }
+//! fn node_id(&'a self, n: &Nd) -> dot::Id<'a> {
+//! dot::Id::new(format!("N{}", n)).unwrap()
+//! }
+//! fn node_label<'b>(&'b self, n: &Nd) -> dot::LabelText<'b> {
+//! dot::LabelText::LabelStr(self.nodes[*n].into())
+//! }
+//! fn edge_label<'b>(&'b self, _: &Ed) -> dot::LabelText<'b> {
+//! dot::LabelText::LabelStr("&sube;".into())
+//! }
+//! }
+//!
+//! impl<'a> dot::GraphWalk<'a> for Graph {
+//! type Node = Nd;
+//! type Edge = Ed<'a>;
+//! fn nodes(&self) -> dot::Nodes<'a,Nd> { (0..self.nodes.len()).collect() }
+//! fn edges(&'a self) -> dot::Edges<'a,Ed<'a>> { self.edges.iter().collect() }
+//! fn source(&self, e: &Ed) -> Nd { let & &(s,_) = e; s }
+//! fn target(&self, e: &Ed) -> Nd { let & &(_,t) = e; t }
+//! }
+//!
+//! # pub fn main() { render_to(&mut Vec::new()) }
+//! ```
+//!
+//! ```no_run
+//! # pub fn render_to<W:std::io::Write>(output: &mut W) { unimplemented!() }
+//! pub fn main() {
+//! use std::fs::File;
+//! let mut f = File::create("example2.dot").unwrap();
+//! render_to(&mut f)
+//! }
+//! ```
+//!
+//! The third example is similar to the second, except now each node and
+//! edge now carries a reference to the string label for each node as well
+//! as that node's index. (This is another illustration of how to share
+//! structure with the graph itself, and why one might want to do so.)
+//!
+//! The output from this example is the same as the second example: the
+//! Hasse-diagram for the subsets of the set `{x, y}`.
+//!
+//! ```rust
+//! #![feature(rustc_private)]
+//!
+//! use std::io::Write;
+//! use rustc_graphviz as dot;
+//!
+//! type Nd<'a> = (usize, &'a str);
+//! type Ed<'a> = (Nd<'a>, Nd<'a>);
+//! struct Graph { nodes: Vec<&'static str>, edges: Vec<(usize,usize)> }
+//!
+//! pub fn render_to<W: Write>(output: &mut W) {
+//! let nodes = vec!["{x,y}","{x}","{y}","{}"];
+//! let edges = vec![(0,1), (0,2), (1,3), (2,3)];
+//! let graph = Graph { nodes: nodes, edges: edges };
+//!
+//! dot::render(&graph, output).unwrap()
+//! }
+//!
+//! impl<'a> dot::Labeller<'a> for Graph {
+//! type Node = Nd<'a>;
+//! type Edge = Ed<'a>;
+//! fn graph_id(&'a self) -> dot::Id<'a> { dot::Id::new("example3").unwrap() }
+//! fn node_id(&'a self, n: &Nd<'a>) -> dot::Id<'a> {
+//! dot::Id::new(format!("N{}", n.0)).unwrap()
+//! }
+//! fn node_label<'b>(&'b self, n: &Nd<'b>) -> dot::LabelText<'b> {
+//! let &(i, _) = n;
+//! dot::LabelText::LabelStr(self.nodes[i].into())
+//! }
+//! fn edge_label<'b>(&'b self, _: &Ed<'b>) -> dot::LabelText<'b> {
+//! dot::LabelText::LabelStr("&sube;".into())
+//! }
+//! }
+//!
+//! impl<'a> dot::GraphWalk<'a> for Graph {
+//! type Node = Nd<'a>;
+//! type Edge = Ed<'a>;
+//! fn nodes(&'a self) -> dot::Nodes<'a,Nd<'a>> {
+//! self.nodes.iter().map(|s| &s[..]).enumerate().collect()
+//! }
+//! fn edges(&'a self) -> dot::Edges<'a,Ed<'a>> {
+//! self.edges.iter()
+//! .map(|&(i,j)|((i, &self.nodes[i][..]),
+//! (j, &self.nodes[j][..])))
+//! .collect()
+//! }
+//! fn source(&self, e: &Ed<'a>) -> Nd<'a> { let &(s,_) = e; s }
+//! fn target(&self, e: &Ed<'a>) -> Nd<'a> { let &(_,t) = e; t }
+//! }
+//!
+//! # pub fn main() { render_to(&mut Vec::new()) }
+//! ```
+//!
+//! ```no_run
+//! # pub fn render_to<W:std::io::Write>(output: &mut W) { unimplemented!() }
+//! pub fn main() {
+//! use std::fs::File;
+//! let mut f = File::create("example3.dot").unwrap();
+//! render_to(&mut f)
+//! }
+//! ```
+//!
+//! # References
+//!
+//! * [Graphviz](https://www.graphviz.org/)
+//!
+//! * [DOT language](https://www.graphviz.org/doc/info/lang.html)
+
+#![doc(
+ html_root_url = "https://doc.rust-lang.org/nightly/nightly-rustc/",
+ test(attr(allow(unused_variables), deny(warnings)))
+)]
+
+use LabelText::*;
+
+use std::borrow::Cow;
+use std::io;
+use std::io::prelude::*;
+
+/// The text for a graphviz label on a node or edge.
+pub enum LabelText<'a> {
+ /// This kind of label preserves the text directly as is.
+ ///
+ /// Occurrences of backslashes (`\`) are escaped, and thus appear
+ /// as backslashes in the rendered label.
+ LabelStr(Cow<'a, str>),
+
+ /// This kind of label uses the graphviz label escString type:
+ /// <https://www.graphviz.org/docs/attr-types/escString>
+ ///
+ /// Occurrences of backslashes (`\`) are not escaped; instead they
+ /// are interpreted as initiating an escString escape sequence.
+ ///
+ /// Escape sequences of particular interest: in addition to `\n`
+ /// to break a line (centering the line preceding the `\n`), there
+ /// are also the escape sequences `\l` which left-justifies the
+ /// preceding line and `\r` which right-justifies it.
+ EscStr(Cow<'a, str>),
+
+ /// This uses a graphviz [HTML string label][html]. The string is
+ /// printed exactly as given, but between `<` and `>`. **No
+ /// escaping is performed.**
+ ///
+ /// [html]: https://www.graphviz.org/doc/info/shapes.html#html
+ HtmlStr(Cow<'a, str>),
+}
+
+/// The style for a node or edge.
+/// See <https://www.graphviz.org/docs/attr-types/style/> for descriptions.
+/// Note that some of these are not valid for edges.
+#[derive(Copy, Clone, PartialEq, Eq, Debug)]
+pub enum Style {
+ None,
+ Solid,
+ Dashed,
+ Dotted,
+ Bold,
+ Rounded,
+ Diagonals,
+ Filled,
+ Striped,
+ Wedged,
+}
+
+impl Style {
+ pub fn as_slice(self) -> &'static str {
+ match self {
+ Style::None => "",
+ Style::Solid => "solid",
+ Style::Dashed => "dashed",
+ Style::Dotted => "dotted",
+ Style::Bold => "bold",
+ Style::Rounded => "rounded",
+ Style::Diagonals => "diagonals",
+ Style::Filled => "filled",
+ Style::Striped => "striped",
+ Style::Wedged => "wedged",
+ }
+ }
+}
+
+// There is a tension in the design of the labelling API.
+//
+// For example, I considered making a `Labeller<T>` trait that
+// provides labels for `T`, and then making the graph type `G`
+// implement `Labeller<Node>` and `Labeller<Edge>`. However, this is
+// not possible without functional dependencies. (One could work
+// around that, but I did not explore that avenue heavily.)
+//
+// Another approach that I actually used for a while was to make a
+// `Label<Context>` trait that is implemented by the client-specific
+// Node and Edge types (as well as an implementation on Graph itself
+// for the overall name for the graph). The main disadvantage of this
+// second approach (compared to having the `G` type parameter
+// implement a Labelling service) that I have encountered is that it
+// makes it impossible to use types outside of the current crate
+// directly as Nodes/Edges; you need to wrap them in newtype'd
+// structs. See e.g., the `No` and `Ed` structs in the examples. (In
+// practice clients using a graph in some other crate would need to
+// provide some sort of adapter shim over the graph anyway to
+// interface with this library).
+//
+// Another approach would be to make a single `Labeller<N,E>` trait
+// that provides three methods (graph_label, node_label, edge_label),
+// and then make `G` implement `Labeller<N,E>`. At first this did not
+// appeal to me, since I had thought I would need separate methods on
+// each data variant for dot-internal identifiers versus user-visible
+// labels. However, the identifier/label distinction only arises for
+// nodes; graphs themselves only have identifiers, and edges only have
+// labels.
+//
+// So in the end I decided to use the third approach described above.
+
+/// `Id` is a Graphviz `ID`.
+pub struct Id<'a> {
+ name: Cow<'a, str>,
+}
+
+impl<'a> Id<'a> {
+ /// Creates an `Id` named `name`.
+ ///
+ /// The caller must ensure that the input conforms to an
+ /// identifier format: it must be a non-empty string made up of
+ /// alphanumeric or underscore characters, not beginning with a
+ /// digit (i.e., the regular expression `[a-zA-Z_][a-zA-Z_0-9]*`).
+ ///
+ /// (Note: this format is a strict subset of the `ID` format
+ /// defined by the DOT language. This function may change in the
+ /// future to accept a broader subset, or the entirety, of DOT's
+ /// `ID` format.)
+ ///
+ /// Passing an invalid string (containing spaces, brackets,
+ /// quotes, ...) will return an empty `Err` value.
+ pub fn new<Name: Into<Cow<'a, str>>>(name: Name) -> Result<Id<'a>, ()> {
+ let name = name.into();
+ match name.chars().next() {
+ Some(c) if c.is_ascii_alphabetic() || c == '_' => {}
+ _ => return Err(()),
+ }
+ if !name.chars().all(|c| c.is_ascii_alphanumeric() || c == '_') {
+ return Err(());
+ }
+
+ Ok(Id { name })
+ }
+
+ pub fn as_slice(&'a self) -> &'a str {
+ &*self.name
+ }
+}
+
+/// Each instance of a type that implements `Label<C>` maps to a
+/// unique identifier with respect to `C`, which is used to identify
+/// it in the generated .dot file. They can also provide more
+/// elaborate (and non-unique) label text that is used in the graphviz
+/// rendered output.
+
+/// The graph instance is responsible for providing the DOT compatible
+/// identifiers for the nodes and (optionally) rendered labels for the nodes and
+/// edges, as well as an identifier for the graph itself.
+pub trait Labeller<'a> {
+ type Node;
+ type Edge;
+
+ /// Must return a DOT compatible identifier naming the graph.
+ fn graph_id(&'a self) -> Id<'a>;
+
+ /// Maps `n` to a unique identifier with respect to `self`. The
+ /// implementor is responsible for ensuring that the returned name
+ /// is a valid DOT identifier.
+ fn node_id(&'a self, n: &Self::Node) -> Id<'a>;
+
+ /// Maps `n` to one of the [graphviz `shape` names][1]. If `None`
+ /// is returned, no `shape` attribute is specified.
+ ///
+ /// [1]: https://www.graphviz.org/doc/info/shapes.html
+ fn node_shape(&'a self, _node: &Self::Node) -> Option<LabelText<'a>> {
+ None
+ }
+
+ /// Maps `n` to a label that will be used in the rendered output.
+ /// The label need not be unique, and may be the empty string; the
+ /// default is just the output from `node_id`.
+ fn node_label(&'a self, n: &Self::Node) -> LabelText<'a> {
+ LabelStr(self.node_id(n).name)
+ }
+
+ /// Maps `e` to a label that will be used in the rendered output.
+ /// The label need not be unique, and may be the empty string; the
+ /// default is in fact the empty string.
+ fn edge_label(&'a self, _e: &Self::Edge) -> LabelText<'a> {
+ LabelStr("".into())
+ }
+
+ /// Maps `n` to a style that will be used in the rendered output.
+ fn node_style(&'a self, _n: &Self::Node) -> Style {
+ Style::None
+ }
+
+ /// Maps `e` to a style that will be used in the rendered output.
+ fn edge_style(&'a self, _e: &Self::Edge) -> Style {
+ Style::None
+ }
+}
+
+/// Escape tags in such a way that it is suitable for inclusion in a
+/// Graphviz HTML label.
+pub fn escape_html(s: &str) -> String {
+ s.replace('&', "&amp;").replace('\"', "&quot;").replace('<', "&lt;").replace('>', "&gt;")
+}
+
+impl<'a> LabelText<'a> {
+ pub fn label<S: Into<Cow<'a, str>>>(s: S) -> LabelText<'a> {
+ LabelStr(s.into())
+ }
+
+ pub fn html<S: Into<Cow<'a, str>>>(s: S) -> LabelText<'a> {
+ HtmlStr(s.into())
+ }
+
+ fn escape_char<F>(c: char, mut f: F)
+ where
+ F: FnMut(char),
+ {
+ match c {
+ // not escaping \\, since Graphviz escString needs to
+ // interpret backslashes; see EscStr above.
+ '\\' => f(c),
+ _ => {
+ for c in c.escape_default() {
+ f(c)
+ }
+ }
+ }
+ }
+ fn escape_str(s: &str) -> String {
+ let mut out = String::with_capacity(s.len());
+ for c in s.chars() {
+ LabelText::escape_char(c, |c| out.push(c));
+ }
+ out
+ }
+
+ /// Renders text as string suitable for a label in a .dot file.
+ /// This includes quotes or suitable delimiters.
+ pub fn to_dot_string(&self) -> String {
+ match *self {
+ LabelStr(ref s) => format!("\"{}\"", s.escape_default()),
+ EscStr(ref s) => format!("\"{}\"", LabelText::escape_str(&s)),
+ HtmlStr(ref s) => format!("<{}>", s),
+ }
+ }
+
+ /// Decomposes content into string suitable for making EscStr that
+ /// yields same content as self. The result obeys the law
+ /// render(`lt`) == render(`EscStr(lt.pre_escaped_content())`) for
+ /// all `lt: LabelText`.
+ fn pre_escaped_content(self) -> Cow<'a, str> {
+ match self {
+ EscStr(s) => s,
+ LabelStr(s) => {
+ if s.contains('\\') {
+ (&*s).escape_default().to_string().into()
+ } else {
+ s
+ }
+ }
+ HtmlStr(s) => s,
+ }
+ }
+
+ /// Puts `suffix` on a line below this label, with a blank line separator.
+ pub fn suffix_line(self, suffix: LabelText<'_>) -> LabelText<'static> {
+ let mut prefix = self.pre_escaped_content().into_owned();
+ let suffix = suffix.pre_escaped_content();
+ prefix.push_str(r"\n\n");
+ prefix.push_str(&suffix);
+ EscStr(prefix.into())
+ }
+}
+
+pub type Nodes<'a, N> = Cow<'a, [N]>;
+pub type Edges<'a, E> = Cow<'a, [E]>;
+
+// (The type parameters in GraphWalk should be associated items,
+// when/if Rust supports such.)
+
+/// GraphWalk is an abstraction over a directed graph = (nodes,edges)
+/// made up of node handles `N` and edge handles `E`, where each `E`
+/// can be mapped to its source and target nodes.
+///
+/// The lifetime parameter `'a` is exposed in this trait (rather than
+/// introduced as a generic parameter on each method declaration) so
+/// that a client impl can choose `N` and `E` that have substructure
+/// that is bound by the self lifetime `'a`.
+///
+/// The `nodes` and `edges` method each return instantiations of
+/// `Cow<[T]>` to leave implementors the freedom to create
+/// entirely new vectors or to pass back slices into internally owned
+/// vectors.
+pub trait GraphWalk<'a> {
+ type Node: Clone;
+ type Edge: Clone;
+
+ /// Returns all the nodes in this graph.
+ fn nodes(&'a self) -> Nodes<'a, Self::Node>;
+ /// Returns all of the edges in this graph.
+ fn edges(&'a self) -> Edges<'a, Self::Edge>;
+ /// The source node for `edge`.
+ fn source(&'a self, edge: &Self::Edge) -> Self::Node;
+ /// The target node for `edge`.
+ fn target(&'a self, edge: &Self::Edge) -> Self::Node;
+}
+
+#[derive(Clone, PartialEq, Eq, Debug)]
+pub enum RenderOption {
+ NoEdgeLabels,
+ NoNodeLabels,
+ NoEdgeStyles,
+ NoNodeStyles,
+
+ Fontname(String),
+ DarkTheme,
+}
+
+/// Renders directed graph `g` into the writer `w` in DOT syntax.
+/// (Simple wrapper around `render_opts` that passes a default set of options.)
+pub fn render<'a, N, E, G, W>(g: &'a G, w: &mut W) -> io::Result<()>
+where
+ N: Clone + 'a,
+ E: Clone + 'a,
+ G: Labeller<'a, Node = N, Edge = E> + GraphWalk<'a, Node = N, Edge = E>,
+ W: Write,
+{
+ render_opts(g, w, &[])
+}
+
+/// Renders directed graph `g` into the writer `w` in DOT syntax.
+/// (Main entry point for the library.)
+pub fn render_opts<'a, N, E, G, W>(g: &'a G, w: &mut W, options: &[RenderOption]) -> io::Result<()>
+where
+ N: Clone + 'a,
+ E: Clone + 'a,
+ G: Labeller<'a, Node = N, Edge = E> + GraphWalk<'a, Node = N, Edge = E>,
+ W: Write,
+{
+ writeln!(w, "digraph {} {{", g.graph_id().as_slice())?;
+
+ // Global graph properties
+ let mut graph_attrs = Vec::new();
+ let mut content_attrs = Vec::new();
+ let font;
+ if let Some(fontname) = options.iter().find_map(|option| {
+ if let RenderOption::Fontname(fontname) = option { Some(fontname) } else { None }
+ }) {
+ font = format!(r#"fontname="{}""#, fontname);
+ graph_attrs.push(&font[..]);
+ content_attrs.push(&font[..]);
+ }
+ if options.contains(&RenderOption::DarkTheme) {
+ graph_attrs.push(r#"bgcolor="black""#);
+ graph_attrs.push(r#"fontcolor="white""#);
+ content_attrs.push(r#"color="white""#);
+ content_attrs.push(r#"fontcolor="white""#);
+ }
+ if !(graph_attrs.is_empty() && content_attrs.is_empty()) {
+ writeln!(w, r#" graph[{}];"#, graph_attrs.join(" "))?;
+ let content_attrs_str = content_attrs.join(" ");
+ writeln!(w, r#" node[{}];"#, content_attrs_str)?;
+ writeln!(w, r#" edge[{}];"#, content_attrs_str)?;
+ }
+
+ let mut text = Vec::new();
+ for n in g.nodes().iter() {
+ write!(w, " ")?;
+ let id = g.node_id(n);
+
+ let escaped = &g.node_label(n).to_dot_string();
+
+ write!(text, "{}", id.as_slice()).unwrap();
+
+ if !options.contains(&RenderOption::NoNodeLabels) {
+ write!(text, "[label={}]", escaped).unwrap();
+ }
+
+ let style = g.node_style(n);
+ if !options.contains(&RenderOption::NoNodeStyles) && style != Style::None {
+ write!(text, "[style=\"{}\"]", style.as_slice()).unwrap();
+ }
+
+ if let Some(s) = g.node_shape(n) {
+ write!(text, "[shape={}]", &s.to_dot_string()).unwrap();
+ }
+
+ writeln!(text, ";").unwrap();
+ w.write_all(&text)?;
+
+ text.clear();
+ }
+
+ for e in g.edges().iter() {
+ let escaped_label = &g.edge_label(e).to_dot_string();
+ write!(w, " ")?;
+ let source = g.source(e);
+ let target = g.target(e);
+ let source_id = g.node_id(&source);
+ let target_id = g.node_id(&target);
+
+ write!(text, "{} -> {}", source_id.as_slice(), target_id.as_slice()).unwrap();
+
+ if !options.contains(&RenderOption::NoEdgeLabels) {
+ write!(text, "[label={}]", escaped_label).unwrap();
+ }
+
+ let style = g.edge_style(e);
+ if !options.contains(&RenderOption::NoEdgeStyles) && style != Style::None {
+ write!(text, "[style=\"{}\"]", style.as_slice()).unwrap();
+ }
+
+ writeln!(text, ";").unwrap();
+ w.write_all(&text)?;
+
+ text.clear();
+ }
+
+ writeln!(w, "}}")
+}
+
+#[cfg(test)]
+mod tests;
diff --git a/compiler/rustc_graphviz/src/tests.rs b/compiler/rustc_graphviz/src/tests.rs
new file mode 100644
index 000000000..154bae4cb
--- /dev/null
+++ b/compiler/rustc_graphviz/src/tests.rs
@@ -0,0 +1,408 @@
+use super::LabelText::{self, EscStr, HtmlStr, LabelStr};
+use super::{render, Edges, GraphWalk, Id, Labeller, Nodes, Style};
+use std::io;
+use std::io::prelude::*;
+use NodeLabels::*;
+
+/// each node is an index in a vector in the graph.
+type Node = usize;
+struct Edge {
+ from: usize,
+ to: usize,
+ label: &'static str,
+ style: Style,
+}
+
+fn edge(from: usize, to: usize, label: &'static str, style: Style) -> Edge {
+ Edge { from, to, label, style }
+}
+
+struct LabelledGraph {
+ /// The name for this graph. Used for labeling generated `digraph`.
+ name: &'static str,
+
+ /// Each node is an index into `node_labels`; these labels are
+ /// used as the label text for each node. (The node *names*,
+ /// which are unique identifiers, are derived from their index
+ /// in this array.)
+ ///
+ /// If a node maps to None here, then just use its name as its
+ /// text.
+ node_labels: Vec<Option<&'static str>>,
+
+ node_styles: Vec<Style>,
+
+ /// Each edge relates a from-index to a to-index along with a
+ /// label; `edges` collects them.
+ edges: Vec<Edge>,
+}
+
+// A simple wrapper around LabelledGraph that forces the labels to
+// be emitted as EscStr.
+struct LabelledGraphWithEscStrs {
+ graph: LabelledGraph,
+}
+
+enum NodeLabels<L> {
+ AllNodesLabelled(Vec<L>),
+ UnlabelledNodes(usize),
+ SomeNodesLabelled(Vec<Option<L>>),
+}
+
+type Trivial = NodeLabels<&'static str>;
+
+impl NodeLabels<&'static str> {
+ fn to_opt_strs(self) -> Vec<Option<&'static str>> {
+ match self {
+ UnlabelledNodes(len) => vec![None; len],
+ AllNodesLabelled(lbls) => lbls.into_iter().map(Some).collect(),
+ SomeNodesLabelled(lbls) => lbls,
+ }
+ }
+
+ fn len(&self) -> usize {
+ match self {
+ &UnlabelledNodes(len) => len,
+ &AllNodesLabelled(ref lbls) => lbls.len(),
+ &SomeNodesLabelled(ref lbls) => lbls.len(),
+ }
+ }
+}
+
+impl LabelledGraph {
+ fn new(
+ name: &'static str,
+ node_labels: Trivial,
+ edges: Vec<Edge>,
+ node_styles: Option<Vec<Style>>,
+ ) -> LabelledGraph {
+ let count = node_labels.len();
+ LabelledGraph {
+ name,
+ node_labels: node_labels.to_opt_strs(),
+ edges,
+ node_styles: match node_styles {
+ Some(nodes) => nodes,
+ None => vec![Style::None; count],
+ },
+ }
+ }
+}
+
+impl LabelledGraphWithEscStrs {
+ fn new(name: &'static str, node_labels: Trivial, edges: Vec<Edge>) -> LabelledGraphWithEscStrs {
+ LabelledGraphWithEscStrs { graph: LabelledGraph::new(name, node_labels, edges, None) }
+ }
+}
+
+fn id_name<'a>(n: &Node) -> Id<'a> {
+ Id::new(format!("N{}", *n)).unwrap()
+}
+
+impl<'a> Labeller<'a> for LabelledGraph {
+ type Node = Node;
+ type Edge = &'a Edge;
+ fn graph_id(&'a self) -> Id<'a> {
+ Id::new(self.name).unwrap()
+ }
+ fn node_id(&'a self, n: &Node) -> Id<'a> {
+ id_name(n)
+ }
+ fn node_label(&'a self, n: &Node) -> LabelText<'a> {
+ match self.node_labels[*n] {
+ Some(l) => LabelStr(l.into()),
+ None => LabelStr(id_name(n).name),
+ }
+ }
+ fn edge_label(&'a self, e: &&'a Edge) -> LabelText<'a> {
+ LabelStr(e.label.into())
+ }
+ fn node_style(&'a self, n: &Node) -> Style {
+ self.node_styles[*n]
+ }
+ fn edge_style(&'a self, e: &&'a Edge) -> Style {
+ e.style
+ }
+}
+
+impl<'a> Labeller<'a> for LabelledGraphWithEscStrs {
+ type Node = Node;
+ type Edge = &'a Edge;
+ fn graph_id(&'a self) -> Id<'a> {
+ self.graph.graph_id()
+ }
+ fn node_id(&'a self, n: &Node) -> Id<'a> {
+ self.graph.node_id(n)
+ }
+ fn node_label(&'a self, n: &Node) -> LabelText<'a> {
+ match self.graph.node_label(n) {
+ LabelStr(s) | EscStr(s) | HtmlStr(s) => EscStr(s),
+ }
+ }
+ fn edge_label(&'a self, e: &&'a Edge) -> LabelText<'a> {
+ match self.graph.edge_label(e) {
+ LabelStr(s) | EscStr(s) | HtmlStr(s) => EscStr(s),
+ }
+ }
+}
+
+impl<'a> GraphWalk<'a> for LabelledGraph {
+ type Node = Node;
+ type Edge = &'a Edge;
+ fn nodes(&'a self) -> Nodes<'a, Node> {
+ (0..self.node_labels.len()).collect()
+ }
+ fn edges(&'a self) -> Edges<'a, &'a Edge> {
+ self.edges.iter().collect()
+ }
+ fn source(&'a self, edge: &&'a Edge) -> Node {
+ edge.from
+ }
+ fn target(&'a self, edge: &&'a Edge) -> Node {
+ edge.to
+ }
+}
+
+impl<'a> GraphWalk<'a> for LabelledGraphWithEscStrs {
+ type Node = Node;
+ type Edge = &'a Edge;
+ fn nodes(&'a self) -> Nodes<'a, Node> {
+ self.graph.nodes()
+ }
+ fn edges(&'a self) -> Edges<'a, &'a Edge> {
+ self.graph.edges()
+ }
+ fn source(&'a self, edge: &&'a Edge) -> Node {
+ edge.from
+ }
+ fn target(&'a self, edge: &&'a Edge) -> Node {
+ edge.to
+ }
+}
+
+fn test_input(g: LabelledGraph) -> io::Result<String> {
+ let mut writer = Vec::new();
+ render(&g, &mut writer).unwrap();
+ let mut s = String::new();
+ Read::read_to_string(&mut &*writer, &mut s)?;
+ Ok(s)
+}
+
+// All of the tests use raw-strings as the format for the expected outputs,
+// so that you can cut-and-paste the content into a .dot file yourself to
+// see what the graphviz visualizer would produce.
+
+#[test]
+fn empty_graph() {
+ let labels: Trivial = UnlabelledNodes(0);
+ let r = test_input(LabelledGraph::new("empty_graph", labels, vec![], None));
+ assert_eq!(
+ r.unwrap(),
+ r#"digraph empty_graph {
+}
+"#
+ );
+}
+
+#[test]
+fn single_node() {
+ let labels: Trivial = UnlabelledNodes(1);
+ let r = test_input(LabelledGraph::new("single_node", labels, vec![], None));
+ assert_eq!(
+ r.unwrap(),
+ r#"digraph single_node {
+ N0[label="N0"];
+}
+"#
+ );
+}
+
+#[test]
+fn single_node_with_style() {
+ let labels: Trivial = UnlabelledNodes(1);
+ let styles = Some(vec![Style::Dashed]);
+ let r = test_input(LabelledGraph::new("single_node", labels, vec![], styles));
+ assert_eq!(
+ r.unwrap(),
+ r#"digraph single_node {
+ N0[label="N0"][style="dashed"];
+}
+"#
+ );
+}
+
+#[test]
+fn single_edge() {
+ let labels: Trivial = UnlabelledNodes(2);
+ let result = test_input(LabelledGraph::new(
+ "single_edge",
+ labels,
+ vec![edge(0, 1, "E", Style::None)],
+ None,
+ ));
+ assert_eq!(
+ result.unwrap(),
+ r#"digraph single_edge {
+ N0[label="N0"];
+ N1[label="N1"];
+ N0 -> N1[label="E"];
+}
+"#
+ );
+}
+
+#[test]
+fn single_edge_with_style() {
+ let labels: Trivial = UnlabelledNodes(2);
+ let result = test_input(LabelledGraph::new(
+ "single_edge",
+ labels,
+ vec![edge(0, 1, "E", Style::Bold)],
+ None,
+ ));
+ assert_eq!(
+ result.unwrap(),
+ r#"digraph single_edge {
+ N0[label="N0"];
+ N1[label="N1"];
+ N0 -> N1[label="E"][style="bold"];
+}
+"#
+ );
+}
+
+#[test]
+fn test_some_labelled() {
+ let labels: Trivial = SomeNodesLabelled(vec![Some("A"), None]);
+ let styles = Some(vec![Style::None, Style::Dotted]);
+ let result = test_input(LabelledGraph::new(
+ "test_some_labelled",
+ labels,
+ vec![edge(0, 1, "A-1", Style::None)],
+ styles,
+ ));
+ assert_eq!(
+ result.unwrap(),
+ r#"digraph test_some_labelled {
+ N0[label="A"];
+ N1[label="N1"][style="dotted"];
+ N0 -> N1[label="A-1"];
+}
+"#
+ );
+}
+
+#[test]
+fn single_cyclic_node() {
+ let labels: Trivial = UnlabelledNodes(1);
+ let r = test_input(LabelledGraph::new(
+ "single_cyclic_node",
+ labels,
+ vec![edge(0, 0, "E", Style::None)],
+ None,
+ ));
+ assert_eq!(
+ r.unwrap(),
+ r#"digraph single_cyclic_node {
+ N0[label="N0"];
+ N0 -> N0[label="E"];
+}
+"#
+ );
+}
+
+#[test]
+fn hasse_diagram() {
+ let labels = AllNodesLabelled(vec!["{x,y}", "{x}", "{y}", "{}"]);
+ let r = test_input(LabelledGraph::new(
+ "hasse_diagram",
+ labels,
+ vec![
+ edge(0, 1, "", Style::None),
+ edge(0, 2, "", Style::None),
+ edge(1, 3, "", Style::None),
+ edge(2, 3, "", Style::None),
+ ],
+ None,
+ ));
+ assert_eq!(
+ r.unwrap(),
+ r#"digraph hasse_diagram {
+ N0[label="{x,y}"];
+ N1[label="{x}"];
+ N2[label="{y}"];
+ N3[label="{}"];
+ N0 -> N1[label=""];
+ N0 -> N2[label=""];
+ N1 -> N3[label=""];
+ N2 -> N3[label=""];
+}
+"#
+ );
+}
+
+#[test]
+fn left_aligned_text() {
+ let labels = AllNodesLabelled(vec![
+ "if test {\
+ \\l branch1\
+ \\l} else {\
+ \\l branch2\
+ \\l}\
+ \\lafterward\
+ \\l",
+ "branch1",
+ "branch2",
+ "afterward",
+ ]);
+
+ let mut writer = Vec::new();
+
+ let g = LabelledGraphWithEscStrs::new(
+ "syntax_tree",
+ labels,
+ vec![
+ edge(0, 1, "then", Style::None),
+ edge(0, 2, "else", Style::None),
+ edge(1, 3, ";", Style::None),
+ edge(2, 3, ";", Style::None),
+ ],
+ );
+
+ render(&g, &mut writer).unwrap();
+ let mut r = String::new();
+ Read::read_to_string(&mut &*writer, &mut r).unwrap();
+
+ assert_eq!(
+ r,
+ r#"digraph syntax_tree {
+ N0[label="if test {\l branch1\l} else {\l branch2\l}\lafterward\l"];
+ N1[label="branch1"];
+ N2[label="branch2"];
+ N3[label="afterward"];
+ N0 -> N1[label="then"];
+ N0 -> N2[label="else"];
+ N1 -> N3[label=";"];
+ N2 -> N3[label=";"];
+}
+"#
+ );
+}
+
+#[test]
+fn simple_id_construction() {
+ let id1 = Id::new("hello");
+ match id1 {
+ Ok(_) => {}
+ Err(..) => panic!("'hello' is not a valid value for id anymore"),
+ }
+}
+
+#[test]
+fn badly_formatted_id() {
+ let id2 = Id::new("Weird { struct : ure } !!!");
+ match id2 {
+ Ok(_) => panic!("graphviz id suddenly allows spaces, brackets and stuff"),
+ Err(..) => {}
+ }
+}