docs.jl

module Docs

import Base.Markdown: @doc_str, @doc_mstr, MD

export doc, @doc

# Basic API / Storage

const modules = Module[]

meta() = current_module().META

macro init ()
    META = esc(:META)
    quote
        if !isdefined(:META)
            const $META = ObjectIdDict()
            doc($META, doc"Documentation metadata for $(string(current_module())).")
            push!(modules, current_module())
            nothing
        end
    end
end

function doc(obj, data)
    meta()[obj] = data
end

function doc(obj)
    for mod in modules
        haskey(mod.META, obj) && return mod.META[obj]
    end
end

function doc(obj::Union(Symbol, AbstractString))
    doc(current_module().(symbol(obj)))
end

# Function / Method support

function newmethod(defs)
    keylen = -1
    key = nothing
    for def in defs
        length(def.sig) > keylen && (keylen = length(def.sig); key = def)
    end
    return key
end

function newmethod(funcs, f)
    applicable = Method[]
    for def in methods(f)
        (!haskey(funcs, def) || funcs[def] != def.func) && push!(applicable, def)
    end
    return newmethod(applicable)
end

function trackmethod(def)
    name = uncurly(unblock(def).args[1].args[1])
    f = esc(name)
    quote
        if $(isexpr(name, Symbol)) && isdefined($(Expr(:quote, name))) && isgeneric($f)
            funcs = [def => def.func for def in methods($f)]
            $(esc(def))
            $f, newmethod(funcs, $f)
        else
            $(esc(def))
            $f, newmethod(methods($f))
        end
    end
end

type FuncDoc
    order::Vector{Method}
    meta::Dict{Method, Any}
    source::Dict{Method, Any}
end

FuncDoc() = FuncDoc(Method[], Dict(), Dict())

getset(coll, key, default) = coll[key] = get(coll, key, default)

function doc(f::Function, m::Method, data, source)
    fd = getset(meta(), f, FuncDoc())
    isa(fd, FuncDoc) || error("Can't document a method when the function already has metadata")
    !haskey(fd.meta, m) && push!(fd.order, m)
    fd.meta[m] = data
    fd.source[m] = source
end

function doc(f::Function)
    docs = []
    for mod in modules
        if haskey(mod.META, f)
            fd = mod.META[f]
            if isa(fd, FuncDoc)
                for m in fd.order
                    push!(docs, fd.meta[m])
                end
            elseif length(docs) == 0
                return fd
            end
        end
    end
    return catdoc(docs...)
end

function doc(f::Function, m::Method)
    for mod in modules
        haskey(mod.META, f) && isa(mod.META[f], FuncDoc) && haskey(mod.META[f].meta, m) &&
            return mod.META[f].meta[m]
    end
end

catdoc() = nothing
catdoc(xs...) = vcat(xs...)

# Modules

function doc(m::Module)
    md = invoke(doc, (Any,), m)
    md == nothing || return md
    readme = Pkg.dir(string(m), "README.md")
    if isfile(readme)
        return Markdown.parse_file(readme)
    end
end

# Keywords

const keywords = Dict{Symbol,Any}()

# Usage macros

isexpr(x::Expr, ts...) = x.head in ts
isexpr{T}(x::T, ts...) = T in ts

function unblock(ex)
    isexpr(ex, :block) || return ex
    exs = filter(ex->!isexpr(ex, :line), ex.args)
    length(exs) == 1 || return ex
    return exs[1]
end

uncurly(ex) = isexpr(ex, :curly) ? ex.args[1] : ex

namify(ex::Expr) = namify(ex.args[1])
namify(sy::Symbol) = sy

function mdify(ex)
    if isa(ex, AbstractString)
        :(@doc_str $(esc(ex)))
    elseif isexpr(ex, :macrocall) && namify(ex) == symbol("@mstr")
        :(@doc_mstr $(esc(ex.args[2])))
    else
        esc(ex)
    end
end

function namedoc(meta, def, name)
    quote
        @init
        $(esc(def))
        doc($(esc(name)), $(mdify(meta)))
        nothing
    end
end

function funcdoc(meta, def)
    quote
        @init
        f, m = $(trackmethod(def))
        doc(f, m, $(mdify(meta)), $(esc(Expr(:quote, def))))
        f
    end
end

function objdoc(meta, def)
    quote
        @init
        f = $(esc(def))
        doc(f, $(mdify(meta)))
        f
    end
end

fexpr(ex) = isexpr(ex, :function) || (isexpr(ex, :(=)) && isexpr(ex.args[1], :call))

function docm(meta, def)
    def′ = unblock(def)
    isexpr(def′, :macro) && return namedoc(meta, def, symbol("@", namify(def′)))
    isexpr(def′, :type) && return namedoc(meta, def, namify(def′.args[2]))
    isexpr(def′, :abstract) && return namedoc(meta, def, namify(def′))
    fexpr(def′) && return funcdoc(meta, def)
    isexpr(def, :macrocall) && (def = namify(def))
    return objdoc(meta, def)
end

function docm(ex)
    haskey(keywords, ex) && return keywords[ex]
    isexpr(ex, :->) && return docm(ex.args...)
    isexpr(ex, :call) && return :(doc($(esc(ex.args[1])), @which $(esc(ex))))
    isexpr(ex, :macrocall) && (ex = namify(ex))
    :(doc($(esc(ex))))
end

macro doc (args...)
    docm(args...)
end

# Metametadata

@doc """
  The Docs module provides the `@doc` macro which can be used
  to set and retreive documentation metadata for Julia objects.
  Please see docs for the `@doc` macro for more info.
  """ Docs

@doc """
  # Documentation
  The `@doc` macro can be used to both set and retrieve documentation /
  metadata. By default, documentation is written as Markdown, but any
  object can be placed before the arrow. For example:

      @doc \"""
        # The Foo Function
        `foo(x)`: Foo the living hell out of `x`.
      \""" ->
      function foo() ...

  The `->` is not required if the object is on the same line, e.g.

      @doc "foo" foo

  # Retrieving Documentation
  You can retrieve docs for functions, macros and other objects as
  follows:

      @doc foo
      @doc @time
      @doc md""

  # Functions & Methods
  Placing documentation before a method definition (e.g. `function foo()
  ...` or `foo() = ...`) will cause that specific method to be
  documented, as opposed to the whole function. Method docs are
  concatenated together in the order they were defined to provide docs
  for the function.
  """ @doc

@doc "`doc(obj)`: Get the doc metadata for `obj`." doc

@doc """
  `catdoc(xs...)`: Combine the documentation metadata `xs` into a single meta object.
  """ catdoc

# Text / HTML objects

import Base: print, writemime

export HTML, @html_str, @html_mstr

export HTML, Text

@doc """
`HTML(s)`: Create an object that renders `s` as html.

    HTML("<div>foo</div>")

You can also use a stream for large amounts of data:

    HTML() do io
      println(io, "<div>foo</div>")
    end
""" ->
type HTML{T}
    content::T
end

function HTML(xs...)
    HTML() do io
        for x in xs
            writemime(io, MIME"text/html"(), x)
        end
    end
end

writemime(io::IO, ::MIME"text/html", h::HTML) = print(io, h.content)
writemime(io::IO, ::MIME"text/html", h::HTML{Function}) = h.content(io)

@doc "Create an `HTML` object from a literal string." ->
macro html_str (s)
    :(HTML($s))
end

@doc (@doc html"") ->
macro html_mstr (s)
    :(HTML($(Base.triplequoted(s))))
end

function catdoc(xs::HTML...)
    HTML() do io
        for x in xs
            writemime(io, MIME"text/html"(), x)
        end
    end
end

export Text, @text_str, @text_mstr

# @doc """
# `Text(s)`: Create an object that renders `s` as plain text.

#     Text("foo")

# You can also use a stream for large amounts of data:

#     Text() do io
#       println(io, "foo")
#     end
# """ ->
type Text{T}
    content::T
end

print(io::IO, t::Text) = print(io, t.content)
print(io::IO, t::Text{Function}) = t.content(io)
writemime(io::IO, ::MIME"text/plain", t::Text) = print(io, t)

@doc "Create a `Text` object from a literal string." ->
macro text_str (s)
    :(Text($s))
end

@doc (@doc text"") ->
macro text_mstr (s)
    :(Text($(Base.triplequoted(s))))
end

function catdoc(xs::Text...)
    Text() do io
        for x in xs
            writemime(io, MIME"text/plain"(), x)
        end
    end
end

# MD support

catdoc(md::MD...) = MD(md...)

# REPL help

function repl_search(s)
    pre = "search:"
    print(pre)
    printmatches(s, completions(s), cols=Base.tty_size()[2]-length(pre))
    println("\n")
end

function repl_corrections(s)
    print("Couldn't find ")
    Markdown.with_output_format(:cyan, STDOUT) do io
        println(io, s)
    end
    print_correction(s)
end

macro repl (ex)
    quote
        # Fuzzy Searching
        $(isexpr(ex, Symbol)) && repl_search($(string(ex)))
        if $(isa(ex, Symbol)) &&
                !(isdefined($(current_module()), $(Expr(:quote, ex))) ||
                  haskey(keywords, $(Expr(:quote, ex))))
            repl_corrections($(string(ex)))
        else
            # Backwards-compatible with the previous help system, for now
            let doc = @doc $(esc(ex))
                doc ≠ nothing ? doc : Base.Help.@help_ $(esc(ex))
            end
        end
    end
end

# Search & Rescue
# Utilities for correcting user mistakes and (eventually)
# doing full documentation searches from the repl.

# Fuzzy Search Algorithm

function matchinds(needle, haystack; acronym = false)
    chars = collect(needle)
    is = Int[]
    lastc = '\0'
    for (i, char) in enumerate(haystack)
        isempty(chars) && break
        while chars[1] == ' ' shift!(chars) end # skip spaces
        if lowercase(char) == lowercase(chars[1]) && (!acronym || !isalpha(lastc))
            push!(is, i)
            shift!(chars)
        end
        lastc = char
    end
    return is
end

longer(x, y) = length(x) ≥ length(y) ? (x, true) : (y, false)

bestmatch(needle, haystack) =
    longer(matchinds(needle, haystack, acronym = true),
           matchinds(needle, haystack))

avgdistance(xs) =
    isempty(xs) ? 0 :
    (xs[end] - xs[1] - length(xs)+1)/length(xs)

function fuzzyscore(needle, haystack)
    score = 0.
    is, acro = bestmatch(needle, haystack)
    score += (acro?2:1)length(is) # Matched characters
    score -= 2(length(needle)-length(is)) # Missing characters
    !acro && (score -= avgdistance(is)/10) # Contiguous
    !isempty(is) && (score -= mean(is)/100) # Closer to beginning
    return score
end

function fuzzysort(search, candidates)
    scores = map(cand -> (fuzzyscore(search, cand), -levenshtein(search, cand)), candidates)
    candidates[sortperm(scores)] |> reverse
end

# Levenshtein Distance

function levenshtein(s1, s2)
    a, b = collect(s1), collect(s2)
    m = length(a)
    n = length(b)
    d = Array(Int, m+1, n+1)

    d[1:m+1, 1] = 0:m
    d[1, 1:n+1] = 0:n

    for i = 1:m, j = 1:n
        d[i+1,j+1] = min(d[i  , j+1] + 1,
                         d[i+1, j  ] + 1,
                         d[i  , j  ] + (a[i] != b[j]))
    end

    return d[m+1, n+1]
end

function levsort(search, candidates)
    scores = map(cand -> (levenshtein(search, cand), -fuzzyscore(search, cand)), candidates)
    candidates = candidates[sortperm(scores)]
    i = 0
    for i = 1:length(candidates)
        levenshtein(search, candidates[i]) > 3 && break
    end
    return candidates[1:i]
end

# Result printing

function printmatch(io::IO, word, match)
    is, _ = bestmatch(word, match)
    Markdown.with_output_format(:fade, io) do io
        for (i, char) = enumerate(match)
            if i in is
                Markdown.with_output_format(print, :bold, io, char)
            else
                print(io, char)
            end
        end
    end
end

printmatch(args...) = printfuzzy(STDOUT, args...)

function printmatches(io::IO, word, matches; cols = Base.tty_size()[2])
    total = 0
    for match in matches
        total + length(match) + 1 > cols && break
        fuzzyscore(word, match) < 0 && break
        print(io, " ")
        printmatch(io, word, match)
        total += length(match) + 1
    end
end

printmatches(args...; cols = Base.tty_size()[2]) = printmatches(STDOUT, args..., cols = cols)

function print_joined_cols(io::IO, ss, delim = "", last = delim; cols = Base.tty_size()[2])
    i = 0
    total = 0
    for i = 1:length(ss)
        total += length(ss[i])
        total + max(i-2,0)*length(delim) + (i>1?1:0)*length(last) > cols && (i-=1; break)
    end
    print_joined(io, ss[1:i], delim, last)
end

print_joined_cols(args...; cols = Base.tty_size()[2]) = print_joined_cols(STDOUT, args...; cols=cols)

function print_correction(word)
    cors = levsort(word, accessible(current_module()))
    pre = "Perhaps you meant "
    print(pre)
    print_joined_cols(cors, ", ", " or "; cols = Base.tty_size()[2]-length(pre))
    println()
    return
end

# Completion data

const builtins = ["abstract", "baremodule", "begin", "bitstype", "break",
                  "catch", "ccall", "const", "continue", "do", "else",
                  "elseif", "end", "export", "finally", "for", "function",
                  "global", "if", "immutable", "import", "importall", "let",
                  "local", "macro", "module", "quote", "return", "try", "type",
                  "typealias", "using", "while"]

moduleusings(mod) = ccall(:jl_module_usings, Any, (Any,), mod)

filtervalid(names) = filter(x->!ismatch(r"#", x), map(string, names))

accessible(mod::Module) =
    [names(mod, true, true);
     map(names, moduleusings(mod))...;
     builtins] |> unique |> filtervalid

completions(name) = fuzzysort(name, accessible(current_module()))
completions(name::Symbol) = completions(string(name))

end