Compare nothing by identity rather than by value

Comparing nothing by value (==, =!) rather than by identity (===, !==)
can have negative consequences on code speed. This commit changes all
nothing comparisons to use the isnothing and issomething utilities
defined in misc.jl for consistency.

src/Gadfly.jl

@@ -388,14 +388,14 @@ function render_prepare(plot::Plot)
     # they are missing.
     datas = Array{Data}(undef, length(plot.layers))
     for (i, layer) in enumerate(plot.layers)
-        if layer.data_source === nothing && isempty(layer.mapping)
+        if isnothing(layer.data_source) && isempty(layer.mapping)
             layer.data_source = plot.data_source
             layer.mapping = plot.mapping
             datas[i] = plot.data
         else
             datas[i] = Data()
 
-            if layer.data_source === nothing
+            if isnothing(layer.data_source)
                 layer.data_source = plot.data_source
             end
 
@@ -416,7 +416,7 @@ function render_prepare(plot::Plot)
         if isa(layer.geom, Geom.SubplotGeometry)
             for subplot_layer in layers(layer.geom)
                 subplot_data = Data()
-                if subplot_layer.data_source === nothing
+                if isnothing(subplot_layer.data_source)
                     subplot_layer.data_source = layer.data_source
                 end
 
@@ -434,7 +434,7 @@ function render_prepare(plot::Plot)
     coord = plot.coord
     for layer in plot.layers
         coord_type = element_coordinate_type(layer.geom)
-        if coord === nothing
+        if isnothing(coord)
             coord = coord_type()
         elseif typeof(coord) != coord_type
             error("Plot uses multiple coordinates: $(typeof(coord)) and $(coord_type)")
@@ -503,7 +503,7 @@ function render_prepare(plot::Plot)
 
     unscaled_aesthetics = setdiff(used_aesthetics, scaled_aesthetics)
 
-    _theme(plt, lyr) = lyr.theme == nothing ? plt.theme : lyr.theme
+    _theme(plt, lyr) = isnothing(lyr.theme) ? plt.theme : lyr.theme
 
     # Add default scales for statistics.
     layer_stats_with_theme = map(plot.layers, layer_stats) do l, stats
@@ -532,17 +532,17 @@ function render_prepare(plot::Plot)
         in(var, mapped_aesthetics) || continue
 
         var_data = getfield(plot.data, var)
-        if var_data == nothing
+        if isnothing(var_data)
             for data in datas
                 var_layer_data = getfield(data, var)
-                if var_layer_data != nothing
+                if issomething(var_layer_data)
                     var_data = var_layer_data
                     break
                 end
             end
         end
 
-        var_data == nothing && continue
+        isnothing(var_data) && continue
 
         t = classify_data(var_data)
         if scale_exists(t, var)
@@ -560,7 +560,7 @@ function render_prepare(plot::Plot)
         t = :categorical
         for data in Iterators.flatten((datas, subplot_datas))
             val = getfield(data, var)
-            if val != nothing && val != :categorical
+            if issomething(val) && val != :categorical
                 t = classify_data(val)
             end
         end
@@ -659,24 +659,27 @@ function render_prepare(plot::Plot)
     keyvars = [:color, :shape]
     for (i, layer) in enumerate(plot.layers)
         for kv in keyvars
-            fflag = (getfield(layer_aess[i], Symbol(kv,"_key_title")) == nothing) && haskey(layer.mapping, kv) && !isa(layer.mapping[kv], AbstractArray)
+            fflag = (isnothing(getfield(layer_aess[i], Symbol(kv,"_key_title")))) &&
+                haskey(layer.mapping, kv) &&
+                !isa(layer.mapping[kv], AbstractArray)
             fflag && setfield!(layer_aess[i], Symbol(kv,"_key_title"), string(layer.mapping[kv]))
         end
     end
 
     for kv in keyvars
-        fflag = (getfield(layer_aess[1], Symbol(kv,"_key_title")) == nothing) && haskey(plot.mapping, kv) && !isa(plot.mapping[kv], AbstractArray)
+        fflag = (isnothing(getfield(layer_aess[1], Symbol(kv,"_key_title")))) &&
+            haskey(plot.mapping, kv) && !isa(plot.mapping[kv], AbstractArray)
         fflag && setfield!(layer_aess[1], Symbol(kv,"_key_title"), string(plot.mapping[kv]))
     end
 
     # Auto-update color scale if shape==color
     catdatas = vcat(datas, subplot_datas)
     shapev = getfield.(catdatas, :shape)
-    di = (shapev.!=nothing) .& (shapev.== getfield.(catdatas, :color))
+    di = issomething.(shapev) .& (shapev.== getfield.(catdatas, :color))
 
     supress_colorkey = false
     for (aes, data) in zip(layer_aess[di], catdatas[di])
-        aes.shape_key_title==nothing && (aes.shape_key_title=aes.color_key_title="Shape")
+        isnothing(aes.shape_key_title) && (aes.shape_key_title=aes.color_key_title="Shape")
         colorf = scales[:color].f
         scales[:color] =  Scale.color_discrete(colorf, levels=scales[:shape].levels, order=scales[:shape].order)
         Scale.apply_scale(scales[:color], [aes], Gadfly.Data(color=getfield(data,:color))  )
@@ -713,7 +716,7 @@ function render_prepare(plot::Plot)
 
     if !supress_keys
         for (KT, kv) in zip(keytypes, keyvars)
-            fflag = !all([getfield(aes, kv)==nothing for aes in [plot_aes, layer_aess...]])
+            fflag = !all([isnothing(getfield(aes, kv)) for aes in [plot_aes, layer_aess...]])
             fflag && !in(KT, explicit_guide_types) &&  push!(guides, KT())
         end
     end
@@ -756,7 +759,7 @@ function render(plot::Plot)
 
     ctx =  pad_inner(root_context, plot.theme.plot_padding...)
 
-    if plot.theme.background_color != nothing
+    if issomething(plot.theme.background_color)
         compose!(ctx, (context(order=-1000000),
                         fill(plot.theme.background_color),
                         stroke(nothing), rectangle()))
@@ -807,7 +810,7 @@ function render_prepared(plot::Plot,
                                           layer_aess), scales)
 
     # IV. Geometries
-    themes = Theme[layer.theme === nothing ? plot.theme : layer.theme
+    themes = Theme[isnothing(layer.theme) ? plot.theme : layer.theme
                    for layer in plot.layers]
     zips = trim_zip(plot.layers, layer_aess, layer_subplot_aess,
                     layer_subplot_datas, themes)
@@ -820,7 +823,7 @@ function render_prepared(plot::Plot,
     guide_contexts = Guide.PositionedGuide[]
     for guide in guides
         guide_context = render(guide, plot.theme, plot_aes, dynamic)
-        if !isnothing(guide_context)
+        if issomething(guide_context)
             append!(guide_contexts, guide_context)
         end
     end

src/aesthetics.jl

@@ -99,7 +99,7 @@ function show(io::IO, data::Aesthetics)
     print(io, "Aesthetics(")
     for name in fieldnames(Aesthetics)
         val = getfield(data, name)
-        if !ismissing(val) && val != nothing
+        if !ismissing(val) && issomething(val)
             print(io, "\n  ", string(name), "=")
             show(io, getfield(data, name))
         end
@@ -137,7 +137,7 @@ getindex(aes::Aesthetics, i::Integer, j::AbstractString) = getfield(aes, Symbol(
 function defined_aesthetics(aes::Aesthetics)
     vars = Set{Symbol}()
     for name in fieldnames(Aesthetics)
-        getfield(aes, name) === nothing || push!(vars, name)
+        isnothing(getfield(aes, name)) || push!(vars, name)
     end
     vars
 end
@@ -169,7 +169,7 @@ function assert_aesthetics_undefined(who::AbstractString, aes::Aesthetics, vars:
 end
 
 function assert_aesthetics_equal_length(who::AbstractString, aes::Aesthetics, vars::Symbol...)
-    defined_vars = Compat.Iterators.filter(var -> !(getfield(aes, var) === nothing), vars)
+    defined_vars = Compat.Iterators.filter(var -> issomething(getfield(aes, var)), vars)
 
     if !isempty(defined_vars)
         n = length(getfield(aes, first(defined_vars)))
@@ -227,18 +227,9 @@ function concat(aess::Aesthetics...)
     cataes = Aesthetics()
     for aes in aess
         for var in fieldnames(Aesthetics)
-            if var in [:xviewmin, :yviewmin]
+            if var in [:xviewmin, :yviewmin, :xviewmax, :yviewmax]
                 mu, mv = getfield(cataes, var), getfield(aes, var)
-                setfield!(cataes, var,
-                          mu === nothing ? mv :
-                             mv == nothing ? mu :
-                                 min(mu, mv))
-            elseif var in [:xviewmax, :yviewmax]
-                mu, mv = getfield(cataes, var), getfield(aes, var)
-                setfield!(cataes, var,
-                          mu === nothing ? mv :
-                             mv == nothing ? mu :
-                                 max(mu, mv))
+                setfield!(cataes, var, isnothing(mu) ? mv : isnothing(mv) ? mu : min(mu, mv))
             else
                 setfield!(cataes, var,
                           cat_aes_var!(getfield(cataes, var), getfield(aes, var)))
@@ -310,21 +301,21 @@ end
 #
 function by_xy_group(aes::T, xgroup, ygroup,
                      num_xgroups, num_ygroups) where T <: Union{Data, Aesthetics}
-    @assert xgroup === nothing || ygroup === nothing || length(xgroup) == length(ygroup)
+    @assert isnothing(xgroup) || isnothing(ygroup) || length(xgroup) == length(ygroup)
 
     n = num_ygroups
     m = num_xgroups
 
-    xrefs = xgroup === nothing ? [1] : xgroup
-    yrefs = ygroup === nothing ? [1] : ygroup
+    xrefs = isnothing(xgroup) ? [1] : xgroup
+    yrefs = isnothing(ygroup) ? [1] : ygroup
 
     aes_grid = Array{T}(undef, n, m)
     staging = Array{AbstractArray}(undef, n, m)
     for i in 1:n, j in 1:m
         aes_grid[i, j] = T()
     end
 
-    xgroup === nothing && ygroup === nothing && return aes_grid
+    isnothing(xgroup) && isnothing(ygroup) && return aes_grid
 
     function make_pooled_array(::Type{IndirectArray{T,N,A,V}}, arr::AbstractArray) where {T,N,A,V}
         uarr = unique(arr)
@@ -347,8 +338,8 @@ function by_xy_group(aes::T, xgroup, ygroup,
 
         vals = getfield(aes, var)
         if typeof(vals) <: AbstractArray
-            if xgroup !== nothing && length(vals) !== length(xgroup) ||
-               ygroup !== nothing && length(vals) !== length(ygroup)
+            if issomething(xgroup) && length(vals) !== length(xgroup) ||
+               issomething(ygroup) && length(vals) !== length(ygroup)
                 continue
             end
 
@@ -402,12 +393,10 @@ function inherit!(a::Aesthetics, b::Aesthetics;
         bval = getfield(b, field)
         if field in clobber_set
             setfield!(a, field, bval)
-        elseif aval === missing || aval === nothing || aval === string || aval == showoff
+        elseif aval === missing || isnothing(aval) || aval === string || aval == showoff
             setfield!(a, field, bval)
-        elseif field == :xviewmin || field == :yviewmin
-            bval != nothing && (aval == nothing || aval > bval) && setfield!(a, field, bval)
-        elseif field == :xviewmax || field == :yviewmax
-            bval != nothing && (aval == nothing || aval < bval) && setfield!(a, field, bval)
+        elseif field in (:xviewmin, :yviewmin, :xviewmax, :yviewmax)
+            issomething(bval) && (isnothing(aval) || aval > bval) && setfield!(a, field, bval)
         elseif typeof(aval) <: Dict && typeof(bval) <: Dict
             merge!(aval, getfield(b, field))
         end

src/coord.jl

@@ -67,7 +67,7 @@ function first_concrete_aesthetic_value(aess::Vector{Gadfly.Aesthetics}, vars::V
     for var in vars
         for aes in aess
             vals = getfield(aes, var)
-            vals === nothing && continue
+            Gadfly.isnothing(vals) && continue
 
             if !isa(vals, AbstractArray)
                 vals = [vals]
@@ -106,7 +106,7 @@ function aesthetics_type(aess::Vector{Gadfly.Aesthetics},
     for var in vars
         for aes in aess
             vals = getfield(aes, var)
-            vals === nothing && continue
+            Gadfly.isnothing(vals) && continue
 
             if var == :outliers
                 if !isempty(vals)
@@ -153,11 +153,11 @@ function apply_coordinate(coord::Cartesian, aess::Vector{Gadfly.Aesthetics},
 
     xmin = xmax = first_concrete_aesthetic_value(aess, coord.xvars)
 
-    if xmin != nothing
+    if Gadfly.issomething(xmin)
         for var in coord.xvars
             for aes in aess
                 vals = getfield(aes, var)
-                vals === nothing && continue
+                Gadfly.isnothing(vals) && continue
 
                 if !isa(vals, AbstractArray)
                     vals = [vals]
@@ -169,11 +169,11 @@ function apply_coordinate(coord::Cartesian, aess::Vector{Gadfly.Aesthetics},
     end
 
     ymin = ymax = first_concrete_aesthetic_value(aess, coord.yvars)
-    if ymin != nothing
+    if Gadfly.issomething(ymin)
         for var in coord.yvars
             for aes in aess
                 vals = getfield(aes, var)
-                vals === nothing && continue
+                Gadfly.isnothing(vals) && continue
 
                 # Outliers is an odd aesthetic that needs special treatment.
                 if var == :outliers
@@ -196,40 +196,40 @@ function apply_coordinate(coord::Cartesian, aess::Vector{Gadfly.Aesthetics},
 
     # viewmin/max that is set explicitly should override min/max
     for aes in aess
-        if aes.xviewmin != nothing
-            xviewmin = xviewmin === nothing ? aes.xviewmin : min(xviewmin, aes.xviewmin)
+        if Gadfly.issomething(aes.xviewmin)
+            xviewmin = Gadfly.isnothing(xviewmin) ? aes.xviewmin : min(xviewmin, aes.xviewmin)
         end
 
-        if aes.xviewmax != nothing
-            xviewmax = xviewmax === nothing ? aes.xviewmax : max(xviewmax, aes.xviewmax)
+        if Gadfly.issomething(aes.xviewmax)
+            xviewmax = Gadfly.isnothing(xviewmax) ? aes.xviewmax : max(xviewmax, aes.xviewmax)
         end
 
-        if aes.yviewmin != nothing
-            yviewmin = yviewmin === nothing ? aes.yviewmin : min(yviewmin, aes.yviewmin)
+        if Gadfly.issomething(aes.yviewmin)
+            yviewmin = Gadfly.isnothing(yviewmin) ? aes.yviewmin : min(yviewmin, aes.yviewmin)
         end
 
-        if aes.yviewmax != nothing
-            yviewmax = yviewmax === nothing ? aes.yviewmax : max(yviewmax, aes.yviewmax)
+        if Gadfly.issomething(aes.yviewmax)
+            yviewmax = Gadfly.isnothing(yviewmax) ? aes.yviewmax : max(yviewmax, aes.yviewmax)
         end
     end
 
-    xmax = xviewmax === nothing ? xmax : max(xmax, xviewmax)
-    xmin = xviewmin === nothing ? xmin : min(xmin, xviewmin)
-    ymax = yviewmax === nothing ? ymax : max(ymax, yviewmax)
-    ymin = yviewmin === nothing ? ymin : min(ymin, yviewmin)
+    xmax = Gadfly.isnothing(xviewmax) ? xmax : max(xmax, xviewmax)
+    xmin = Gadfly.isnothing(xviewmin) ? xmin : min(xmin, xviewmin)
+    ymax = Gadfly.isnothing(yviewmax) ? ymax : max(ymax, yviewmax)
+    ymin = Gadfly.isnothing(yviewmin) ? ymin : min(ymin, yviewmin)
 
     # Hard limits set in Coord should override everything else
-    xmin = coord.xmin === nothing ? xmin : coord.xmin
-    xmax = coord.xmax === nothing ? xmax : coord.xmax
-    ymin = coord.ymin === nothing ? ymin : coord.ymin
-    ymax = coord.ymax === nothing ? ymax : coord.ymax
+    xmin = Gadfly.isnothing(coord.xmin) ? xmin : coord.xmin
+    xmax = Gadfly.isnothing(coord.xmax) ? xmax : coord.xmax
+    ymin = Gadfly.isnothing(coord.ymin) ? ymin : coord.ymin
+    ymax = Gadfly.isnothing(coord.ymax) ? ymax : coord.ymax
 
-    if xmin === nothing || !isfinite(xmin)
+    if Gadfly.isnothing(xmin) || !isfinite(xmin)
         xmin = 0.0
         xmax = 1.0
     end
 
-    if ymin === nothing || !isfinite(ymin)
+    if Gadfly.isnothing(ymin) || !isfinite(ymin)
         ymin = 0.0
         ymax = 1.0
     end

src/data.jl

@@ -76,7 +76,7 @@ function show(io::IO, data::Data)
     maxlen = 0
     print(io, "Data(")
     for name in fieldnames(Data)
-        if getfield(data, name) != nothing
+        if issomething(getfield(data, name))
             print(io, "\n  ", string(name), "=")
             show(io, getfield(data, name))
         end

src/dataframes.jl

@@ -11,7 +11,7 @@ function meltdata(U::AbstractDataFrame, colgroups_::Vector{Col.GroupedColumn})
     vm = um
     grouped_columns = Set{Symbol}()
     for colgroup in colgroups
-        if colgroup.columns===nothing # null => group all columns
+        if isnothing(colgroup.columns) # null => group all columns
             vm *= un
             grouped_columns = copy(allcolumns)
         else
@@ -34,7 +34,7 @@ function meltdata(U::AbstractDataFrame, colgroups_::Vector{Col.GroupedColumn})
 
     # allocate vectors for grouped columns
     for (j, colgroup) in enumerate(colgroups)
-        cols = colgroup.columns===nothing ? allcolumns : colgroup.columns
+        cols = isnothing(colgroup.columns) ? allcolumns : colgroup.columns
 
         # figure the grouped common column type
         firstcol = U[first(cols)]
@@ -64,7 +64,7 @@ function meltdata(U::AbstractDataFrame, colgroups_::Vector{Col.GroupedColumn})
     col_indicators = Array{Symbol}(undef, vm, length(colgroups))
     row_indicators = Array{Int}(undef, vm, length(colgroups))
 
-    colidxs = [colgroup.columns===nothing ? collect(allcolumns) : colgroup.columns
+    colidxs = [isnothing(colgroup.columns) ? collect(allcolumns) : colgroup.columns
                for colgroup in colgroups]
 
     vi = 1