Add support for Python % format spec (#76)

Author: ScottPJones

Project.toml

@@ -23,7 +23,7 @@ keywords = ["Strings", "Formatting"]
 license = "MIT"
 name = "Format"
 uuid = "1fa38f19-a742-5d3f-a2b9-30dd87b9d5f8"
-version = "1.3.5"
+version = "1.3.6"
 
 [deps]
 

src/fmtcore.jl

@@ -190,6 +190,9 @@ end
 ### print floating point numbers
 
 function _pfmt_f(out::IO, fs::FormatSpec, x::AbstractFloat)
+    # Handle %
+    percentflag = (fs.typ == '%')
+    percentflag && (x *= 100)
     # separate sign, integer, and decimal part
     prec = fs.prec
     rax = round(abs(x); digits = prec)
@@ -200,7 +203,7 @@ function _pfmt_f(out::IO, fs::FormatSpec, x::AbstractFloat)
     # calculate length
     xlen = ndigits(intv)
     numsep, numini = fs.tsep ? divrem(xlen - 1, 3) : (0, 0)
-    xlen += ifelse(prec > 0, prec + 1, 0) + (sch != '\0') + numsep
+    xlen += ifelse(prec > 0, prec + 1, 0) + (sch != '\0') + numsep + percentflag
 
     # calculate padding needed
     pad = fs.width - xlen
@@ -237,6 +240,10 @@ function _pfmt_f(out::IO, fs::FormatSpec, x::AbstractFloat)
         nd < prec && _repprint(out, '0', prec - nd)
         _outint(out, idecv)
     end
+
+    # print trailing percent sign
+    percentflag && print(out, '%')
+
     # right padding
     postpad == 0 || _repprint(out, fs.fill, postpad)
 end

src/fmtspec.jl

@@ -9,19 +9,19 @@
 #  width ::= <integer>
 #  prec  ::= <integer>
 #  type  ::= 'b' | 'c' | 'd' | 'e' | 'E' | 'f' | 'F' | 'g' | 'G' |
-#            'n' | 'o' | 'x' | 'X' | 's'
+#            'n' | 'o' | 'x' | 'X' | 's' | '%'
 #
 # Please refer to http://docs.python.org/2/library/string.html#formatspec
 # for more details
 #
 
 ## FormatSpec type
 
-const _numtypchars = Set(['b', 'd', 'e', 'E', 'f', 'F', 'g', 'G', 'n', 'o', 'x', 'X'])
+const _numtypchars = Set(['b', 'd', 'e', 'E', 'f', 'F', 'g', 'G', 'n', 'o', 'x', 'X', '%'])
 
 _tycls(c::AbstractChar) =
     (c == 'd' || c == 'n' || c == 'b' || c == 'o' || c == 'x') ? 'i' :
-    (c == 'e' || c == 'f' || c == 'g') ? 'f' :
+    (c == 'e' || c == 'f' || c == 'g' || c == '%') ? 'f' :
     (c == 'c') ? 'c' :
     (c == 's') ? 's' :
     error("Invalid type char $(c)")
@@ -108,7 +108,7 @@ end
 
 ## parse FormatSpec from a string
 
-const _spec_regex = r"^(.?[<^>])?([ +-])?(#)?(\d+)?([,_])?(.\d+)?([bcdeEfFgGnosxX])?$"
+const _spec_regex = r"^(.?[<^>])?([ +-])?(#)?(\d+)?([,_])?(.\d+)?([bcdeEfFgGnosxX%])?$"
 
 function FormatSpec(s::AbstractString)
     # default spec
@@ -204,7 +204,7 @@ function printfmt(io::IO, fs::FormatSpec, x)
     elseif cls == 'f'
         fx = float(x)
         if isfinite(fx)
-            ty == 'f' || ty == 'F' ? _pfmt_f(io, fs, fx) :
+            ty == 'f' || ty == 'F' || ty == '%' ? _pfmt_f(io, fs, fx) :
             ty == 'e' || ty == 'E' ? _pfmt_e(io, fs, fx) : _pfmt_g(io, fs, fx)
         else
             _pfmt_specialf(io, fs, fx)

test/fmtspec.jl

@@ -344,6 +344,13 @@ end
     @test pyfmt(".1e", 0.0006) == "6.0e-04"
 end
 
+@testset "Format percentage (%)" begin
+    @test pyfmt("8.2%", 0.123456)  == "  12.35%"
+    @test pyfmt("<8.2%", 0.123456) == "12.35%  "
+    @test pyfmt("^8.2%", 0.123456) == " 12.35% "
+    @test pyfmt(">8.2%", 0.123456) == "  12.35%"
+end
+
 @testset "Format special floating point value" begin
 
     @test pyfmt("f", NaN) == "NaN"