Merge pull request #5706 from mbauman/showdict

RFC: Moderately improved dict printing

base/dict.jl

@@ -11,35 +11,132 @@ function in(p::(Any,Any), a::Associative)
  !is(v, secret_table_token) && (v == p[2])
 end
 
-function show{K,V}(io::IO, t::Associative{K,V})
- if isempty(t)
- print(io, typeof(t),"()")
- else
- if K === Any && V === Any
- delims = ['{','}']
- else
- delims = ['[',']']
- end
+function summary(t::Associative)
+ n = length(t)
+ string(typeof(t), " with ", n, (n==1 ? " entry" : " entries"))
+end
+
+function showcompact{K,V}(io::IO, t::Associative{K,V})
+ print(io, summary(t))
+ if !isempty(t)
+ print(io, ": ")
+ delims = (K == V == Any) ? ('{', '}') : ('[', ']')
  print(io, delims[1])
  first = true
- for (k, v) = t
- first || print(io, ',')
- first = false
- show(io, k)
+ for (k, v) in t
+ first || (print(io, ','); first = false)
+ showcompact(io, k)
  print(io, "=>")
- show(io, v)
+ showcompact(io, v)
  end
  print(io, delims[2])
  end
 end
 
+function _truncate_at_width_or_chars(str, width, chars="", truncmark="…")
+ truncwidth = strwidth(truncmark)
+ (width <= 0 || width < truncwidth) && return ""
+ width == truncwidth && return bytestring(truncmark)
+
+ wid = truncidx = lastidx = 0
+ idx = start(str)
+ while !done(str, idx)
+ lastidx = idx
+ c, idx = next(str, idx)
+ wid += charwidth(c)
+ wid >= width - truncwidth && truncidx == 0 && (truncidx = lastidx)
+ (wid >= width || c in chars) && break
+ end
+
+ str[lastidx] in chars && (lastidx = prevind(str, lastidx))
+ truncidx == 0 && (truncidx = lastidx)
+ if lastidx < sizeof(str)
+ return bytestring(SubString(str, 1, truncidx) * truncmark)
+ else
+ return bytestring(str)
+ end
+end
+
+function showdict{K,V}(io::IO, t::Associative{K,V}, limit_output::Bool = false,
+ rows = tty_rows()-3, cols = tty_cols())
+ print(io, summary(t))
+ isempty(t) && return
+ print(io, ":")
+
+ if limit_output
+ rows < 2 && (print(io, " …"); return)
+ cols < 12 && (cols = 12) # Minimum widths of 2 for key, 4 for value
+ cols -= 6 # Subtract the widths of prefix " " separator " => "
+ rows -= 2 # Subtract the summary and final ⋮ continuation lines
+
+ # determine max key width to align the output, caching the strings
+ ks = Array(String, min(rows, length(t)))
+ keylen = 0
+ for (i, k) in enumerate(keys(t))
+ i > rows && break
+ ks[i] = sprint(show, k)
+ keylen = clamp(length(ks[i]), keylen, div(cols, 3))
+ end
+ end
+
+ for (i, (k, v)) in enumerate(t)
+ print(io, "\n ")
+ limit_output && i > rows && (print(io, rpad("⋮", keylen), " => ⋮"); break)
+
+ if limit_output
+ key = rpad(_truncate_at_width_or_chars(ks[i], keylen, "\r\n"), keylen)
+ else
+ key = sprint(show, k)
+ end
+ print(io, key)
+ print(io, " => ")
+
+ val = sprint(show, v)
+ if limit_output
+ val = _truncate_at_width_or_chars(val, cols - keylen, "\r\n")
+ end
+ print(io, val)
+ end
+end
+
+show{K,V}(io::IO, t::Associative{K,V}) = showdict(io, t, false)
+showlimited{K,V}(io::IO, t::Associative{K,V}) = showdict(io, t, true)
+
 immutable KeyIterator{T<:Associative}
  dict::T
 end
 immutable ValueIterator{T<:Associative}
  dict::T
 end
 
+summary{T<:Union(KeyIterator,ValueIterator)}(iter::T) =
+ string(T.name, " for a ", summary(iter.dict))
+
+show(io::IO, iter::Union(KeyIterator,ValueIterator)) = showkv(io, iter, false)
+showlimited(io::IO, iter::Union(KeyIterator,ValueIterator)) = showkv(io, iter, true)
+
+function showkv{T<:Union(KeyIterator,ValueIterator)}(io::IO, iter::T, limit_output::Bool = false,
+ rows = tty_rows()-3, cols = tty_cols())
+ print(io, summary(iter))
+ isempty(iter) && return
+ print(io, ". ", T<:KeyIterator ? "Keys" : "Values", ":")
+ if limit_output
+ rows < 2 && (print(io, " …"); return)
+ cols < 4 && (cols = 4)
+ cols -= 2 # For prefix " "
+ rows -= 2 # For summary and final ⋮ continuation lines
+ end
+
+ for (i, v) in enumerate(iter)
+ print(io, "\n ")
+ limit_output && i >= rows && (print(io, "⋮"); break)
+
+ str = sprint(show, v)
+ limit_output && (str = _truncate_at_width_or_chars(str, cols, "\r\n"))
+ print(io, str)
+ end
+end
+
 length(v::Union(KeyIterator,ValueIterator)) = length(v.dict)
 isempty(v::Union(KeyIterator,ValueIterator)) = isempty(v.dict)
 eltype(v::KeyIterator) = eltype(v.dict)[1]

test/collections.jl

@@ -171,6 +171,39 @@ let f(x) = x^2,
  @test d == {8=>19, 19=>2, 42=>4}
 end
 
+# show
+for d in (["\n" => "\n", "1" => "\n", "\n" => "2"],
+ [string(i) => i for i = 1:30],
+ [reshape(1:i^2,i,i) => reshape(1:i^2,i,i) for i = 1:24],
+ [utf8(Char['α':'α'+i]) => utf8(Char['α':'α'+i]) for i = (1:10)*10])
+ for cols in (12, 40, 80), rows in (2, 10, 24)
+ # Ensure output is limited as requested
+ s = IOBuffer()
+ Base.showdict(s, d, true, rows, cols)
+ out = split(takebuf_string(s),'\n')
+ for line in out[2:end]
+ @test strwidth(line) <= cols
+ end
+ @test length(out) <= rows
+
+ for f in (keys, values)
+ s = IOBuffer()
+ Base.showkv(s, f(d), true, rows, cols)
+ out = split(takebuf_string(s),'\n')
+ for line in out[2:end]
+ @test strwidth(line) <= cols
+ end
+ @test length(out) <= rows
+ end
+ end
+ # Simply ensure these do not throw errors
+ Base.showdict(IOBuffer(), d, false)
+ @test !isempty(summary(d))
+ @test !isempty(summary(keys(d)))
+ @test !isempty(summary(values(d)))
+end
+
+
 # issue #2540
 d = {x => 1
  for x in ['a', 'b', 'c']}