Fix E notation parsing in BigDecimal (#9577)

crystal-lang · Mar 20, 2022 · ecb97a9 · ecb97a9
1 parent 91ac123
commit ecb97a9
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Showing 2 changed files with 77 additions and 5 deletions.
diff --git a/spec/std/big/big_decimal_spec.cr b/spec/std/big/big_decimal_spec.cr
@@ -109,6 +109,74 @@ describe BigDecimal do
     expect_raises(InvalidBigDecimalException) do
       BigDecimal.new("1.2a")
     end
+
+    expect_raises(InvalidBigDecimalException) do
+      BigDecimal.new("1ee1")
+    end
+
+    expect_raises(InvalidBigDecimalException) do
+      BigDecimal.new("e+e1")
+    end
+
+    expect_raises(InvalidBigDecimalException) do
+      BigDecimal.new("1e1e")
+    end
+
+    expect_raises(InvalidBigDecimalException) do
+      BigDecimal.new("1 e1")
+    end
+
+    expect_raises(InvalidBigDecimalException) do
+      BigDecimal.new("..e1")
+    end
+
+    expect_raises(InvalidBigDecimalException) do
+      BigDecimal.new("-..e1")
+    end
+
+    expect_raises(InvalidBigDecimalException) do
+      BigDecimal.new("e1")
+    end
+
+    expect_raises(InvalidBigDecimalException) do
+      BigDecimal.new("e+5")
+    end
+
+    expect_raises(InvalidBigDecimalException) do
+      BigDecimal.new(".e1")
+    end
+
+    expect_raises(InvalidBigDecimalException) do
+      BigDecimal.new(".e+1")
+    end
+
+    expect_raises(InvalidBigDecimalException) do
+      BigDecimal.new("-.e1")
+    end
+
+    expect_raises(InvalidBigDecimalException) do
+      BigDecimal.new("1e.")
+    end
+
+    expect_raises(InvalidBigDecimalException) do
+      BigDecimal.new("1e0.1")
+    end
+
+    expect_raises(InvalidBigDecimalException) do
+      BigDecimal.new("1e+")
+    end
+
+    expect_raises(InvalidBigDecimalException) do
+      BigDecimal.new("1.1e-")
+    end
+
+    expect_raises(InvalidBigDecimalException) do
+      BigDecimal.new("-")
+    end
+
+    expect_raises(InvalidBigDecimalException) do
+      BigDecimal.new("1.0e")
+    end
   end
 
   it "performs arithmetic with bigdecimals" do

diff --git a/src/big/big_decimal.cr b/src/big/big_decimal.cr
@@ -76,23 +76,27 @@ struct BigDecimal < Number
     # Check str's validity and find index of 'e'
     exponent_index = nil
 
+    input_length = str.bytesize
+
     str.each_char_with_index do |char, index|
+      final_character = index == input_length - 1
+      first_character = index == 0
       case char
       when '-'
-        unless index == 0 || exponent_index == index - 1
+        unless (first_character && !final_character) || (exponent_index == index - 1 && !final_character)
           raise InvalidBigDecimalException.new(str, "Unexpected '-' character")
         end
       when '+'
-        unless exponent_index == index - 1
+        if final_character || exponent_index != index - 1
           raise InvalidBigDecimalException.new(str, "Unexpected '+' character")
         end
       when '.'
-        if decimal_index
+        if decimal_index || exponent_index
           raise InvalidBigDecimalException.new(str, "Unexpected '.' character")
         end
         decimal_index = index
       when 'e', 'E'
-        if exponent_index
+        if first_character || final_character || exponent_index || decimal_index == index - 1
           raise InvalidBigDecimalException.new(str, "Unexpected #{char.inspect} character")
         end
         exponent_index = index
@@ -103,7 +107,7 @@ struct BigDecimal < Number
       end
     end
 
-    decimal_end_index = (exponent_index || str.bytesize) - 1
+    decimal_end_index = (exponent_index || input_length) - 1
     if decimal_index
       decimal_count = (decimal_end_index - decimal_index).to_u64