Merge pull request #43 from zeari/decimal_si

	add decimal_si_to_f

lib/more_core_extensions/core_ext/string.rb

@@ -1,3 +1,4 @@
 require 'more_core_extensions/core_ext/string/formats'
 require 'more_core_extensions/core_ext/string/hex_dump'
 require 'more_core_extensions/core_ext/string/iec60027_2'
+require 'more_core_extensions/core_ext/string/decimal_suffix'

lib/more_core_extensions/core_ext/string/decimal_suffix.rb

@@ -0,0 +1,17 @@
+module MoreCoreExtensions
+  module DecimalSI
+    DECIMAL_SUFFIXES = {"d" => 1e-1, "c" => 1e-2, "m" => 1e-3, "μ" => 1e-6, "n" => 1e-9, "p" => 1e-12, "f" => 1e-15,
+                        "a" => 1e-18, "h" => 1e2, "k" => 1e3, "M" => 1e6, "G" => 1e9, "T" => 1e12, "P" => 1e15,
+                        "E" => 1e18}.freeze
+    def decimal_si_to_f
+      multiplier = DECIMAL_SUFFIXES[self[-1]]
+      if multiplier
+        Float(self[0..-2]) * multiplier
+      else
+        Float(self)
+      end
+    end
+  end
+end
+
+String.send(:prepend, MoreCoreExtensions::DecimalSI)

spec/core_ext/string/decimal_suffix_spec.rb

@@ -0,0 +1,21 @@
+describe String do
+  it '#decimal_si_to_f' do
+    expect("1f".decimal_si_to_f).to eq(0.000_000_000_000_001)
+    expect("1p".decimal_si_to_f).to eq(0.000_000_000_001)
+    expect("1n".decimal_si_to_f).to eq(0.000_000_001)
+    expect("1μ".decimal_si_to_f).to eq(0.000_001)
+    expect("1m".decimal_si_to_f).to eq(0.001)
+    expect("1c".decimal_si_to_f).to eq(0.01)
+    expect("1d".decimal_si_to_f).to eq(0.1)
+    expect("1".decimal_si_to_f).to  eq(1.0)
+    expect("1k".decimal_si_to_f).to eq(1_000.0)
+    expect("1M".decimal_si_to_f).to eq(1_000_000.0)
+    expect("1G".decimal_si_to_f).to eq(1_000_000_000.0)
+    expect("1T".decimal_si_to_f).to eq(1_000_000_000_000.0)
+    expect("1P".decimal_si_to_f).to eq(1_000_000_000_000_000.0)
+    expect("1E".decimal_si_to_f).to eq(1_000_000_000_000_000_000.0)
+
+    expect("1e9".decimal_si_to_f).to eq(1_000_000_000.0)
+    expect("1e-9".decimal_si_to_f).to eq(0.000_000_001)
+  end
+end