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authorJean Boussier <jean.boussier@gmail.com>2021-10-18 16:23:54 +0200
committerJean Boussier <jean.boussier@gmail.com>2021-10-26 22:27:30 +0200
commite5319dc9856298f38aa9cdc6ed55e39ad0e8e070 (patch)
tree7c1d685ae65979ce2ae3bee4ccce54507d3f49f8
parent717ab0bb2ee63dfe76076e0c9f91fbac3a0de4fd (diff)
pack.c: add an offset argument to unpack and unpack1
[Feature #18254] This is useful to avoid repeteadly copying strings when parsing binary formats
-rw-r--r--pack.c19
-rw-r--r--pack.rb31
-rw-r--r--spec/ruby/core/string/unpack/shared/basic.rb20
-rw-r--r--spec/ruby/core/string/unpack1_spec.rb20
-rw-r--r--test/ruby/test_pack.rb26
5 files changed, 103 insertions, 13 deletions
diff --git a/pack.c b/pack.c
index e6a729ab089..1fbbd724d78 100644
--- a/pack.c
+++ b/pack.c
@@ -944,7 +944,7 @@ hex2num(char c)
#define UNPACK_1 2
static VALUE
-pack_unpack_internal(VALUE str, VALUE fmt, int mode)
+pack_unpack_internal(VALUE str, VALUE fmt, int mode, long offset)
{
#define hexdigits ruby_hexdigits
char *s, *send;
@@ -973,8 +973,15 @@ pack_unpack_internal(VALUE str, VALUE fmt, int mode)
StringValue(str);
StringValue(fmt);
+
+ if (offset < 0) rb_raise(rb_eArgError, "offset can't be negative");
+ len = RSTRING_LEN(str);
+ if (offset > len) rb_raise(rb_eArgError, "offset outside of string");
+
s = RSTRING_PTR(str);
- send = s + RSTRING_LEN(str);
+ send = s + len;
+ s += offset;
+
p = RSTRING_PTR(fmt);
pend = p + RSTRING_LEN(fmt);
@@ -1614,16 +1621,16 @@ pack_unpack_internal(VALUE str, VALUE fmt, int mode)
}
static VALUE
-pack_unpack(rb_execution_context_t *ec, VALUE str, VALUE fmt)
+pack_unpack(rb_execution_context_t *ec, VALUE str, VALUE fmt, VALUE offset)
{
int mode = rb_block_given_p() ? UNPACK_BLOCK : UNPACK_ARRAY;
- return pack_unpack_internal(str, fmt, mode);
+ return pack_unpack_internal(str, fmt, mode, RB_NUM2LONG(offset));
}
static VALUE
-pack_unpack1(rb_execution_context_t *ec, VALUE str, VALUE fmt)
+pack_unpack1(rb_execution_context_t *ec, VALUE str, VALUE fmt, VALUE offset)
{
- return pack_unpack_internal(str, fmt, UNPACK_1);
+ return pack_unpack_internal(str, fmt, UNPACK_1, RB_NUM2LONG(offset));
}
int
diff --git a/pack.rb b/pack.rb
index e4d629e0f22..8f01861dc9f 100644
--- a/pack.rb
+++ b/pack.rb
@@ -148,10 +148,11 @@ end
class String
# call-seq:
# str.unpack(format) -> anArray
+ # str.unpack(format, offset: anInteger) -> anArray
#
# Decodes <i>str</i> (which may contain binary data) according to the
- # format string, returning an array of each value extracted. The
- # format string consists of a sequence of single-character directives,
+ # format string, returning an array of each value extracted.
+ # The format string consists of a sequence of single-character directives,
# summarized in the table at the end of this entry.
# Each directive may be followed
# by a number, indicating the number of times to repeat with this
@@ -161,7 +162,15 @@ class String
# exclamation mark (``<code>!</code>'') to use the underlying
# platform's native size for the specified type; otherwise, it uses a
# platform-independent consistent size. Spaces are ignored in the
- # format string. See also String#unpack1, Array#pack.
+ # format string.
+ #
+ # The keyword <i>offset</i> can be given to start the decoding after skipping
+ # the specified amount of bytes:
+ # "abc".unpack("C*") # => [97, 98, 99]
+ # "abc".unpack("C*", offset: 2) # => [99]
+ # "abc".unpack("C*", offset: 4) # => offset outside of string (ArgumentError)
+ #
+ # See also String#unpack1, Array#pack.
#
# "abc \0\0abc \0\0".unpack('A6Z6') #=> ["abc", "abc "]
# "abc \0\0".unpack('a3a3') #=> ["abc", " \000\000"]
@@ -263,15 +272,23 @@ class String
# * J, J! j, and j! are available since Ruby 2.3.
# * Q_, Q!, q_, and q! are available since Ruby 2.1.
# * I!<, i!<, I!>, and i!> are available since Ruby 1.9.3.
- def unpack(fmt)
- Primitive.pack_unpack(fmt)
+ def unpack(fmt, offset: 0)
+ Primitive.pack_unpack(fmt, offset)
end
# call-seq:
# str.unpack1(format) -> obj
+ # str.unpack1(format, offset: anInteger) -> obj
#
# Decodes <i>str</i> (which may contain binary data) according to the
# format string, returning the first value extracted.
+ #
+ # The keyword <i>offset</i> can be given to start the decoding after skipping
+ # the specified amount of bytes:
+ # "abc".unpack1("C*") # => 97
+ # "abc".unpack1("C*", offset: 2) # => 99
+ # "abc".unpack1("C*", offset: 4) # => offset outside of string (ArgumentError)
+ #
# See also String#unpack, Array#pack.
#
# Contrast with String#unpack:
@@ -287,7 +304,7 @@ class String
#
# Thus unpack1 is convenient, makes clear the intention and signals
# the expected return value to those reading the code.
- def unpack1(fmt)
- Primitive.pack_unpack1(fmt)
+ def unpack1(fmt, offset: 0)
+ Primitive.pack_unpack1(fmt, offset)
end
end
diff --git a/spec/ruby/core/string/unpack/shared/basic.rb b/spec/ruby/core/string/unpack/shared/basic.rb
index 332e39d8d19..f636f4689fe 100644
--- a/spec/ruby/core/string/unpack/shared/basic.rb
+++ b/spec/ruby/core/string/unpack/shared/basic.rb
@@ -16,6 +16,12 @@ describe :string_unpack_basic, shared: true do
it "raises a TypeError when passed an Integer" do
-> { "abc".unpack(1) }.should raise_error(TypeError)
end
+
+ ruby_version_is "3.1" do
+ it "starts unpacking from the given offset" do
+ "abc".unpack("CC", offset: 1).should == [98, 99]
+ end
+ end
end
describe :string_unpack_no_platform, shared: true do
@@ -26,4 +32,18 @@ describe :string_unpack_no_platform, shared: true do
it "raises an ArgumentError when the format modifier is '!'" do
-> { "abcdefgh".unpack(unpack_format("!")) }.should raise_error(ArgumentError)
end
+
+ ruby_version_is "3.1" do
+ it "raises an ArgumentError when the offset is negative" do
+ -> { "a".unpack("C", offset: -1) }.should raise_error(ArgumentError)
+ end
+
+ it "returns nil if the offset is at the end of the string" do
+ "a".unpack("C", offset: 1).should == [nil]
+ end
+
+ it "raises an ArgumentError when the offset is larget than the string" do
+ -> { "a".unpack("C", offset: 2) }.should raise_error(ArgumentError)
+ end
+ end
end
diff --git a/spec/ruby/core/string/unpack1_spec.rb b/spec/ruby/core/string/unpack1_spec.rb
index 5fe81733fb7..f59bd92d6ad 100644
--- a/spec/ruby/core/string/unpack1_spec.rb
+++ b/spec/ruby/core/string/unpack1_spec.rb
@@ -7,4 +7,24 @@ describe "String#unpack1" do
"aG9nZWZ1Z2E=".unpack1("m").should == "hogefuga"
"A".unpack1("B*").should == "01000001"
end
+
+ ruby_version_is "3.1" do
+ it "starts unpacking from the given offset" do
+ "ZZABCD".unpack1('x3C', offset: 2).should == "ABCD".unpack('x3C')[0]
+ "ZZZZaG9nZWZ1Z2E=".unpack1("m", offset: 4).should == "hogefuga"
+ "ZA".unpack1("B*", offset: 1).should == "01000001"
+ end
+
+ it "raises an ArgumentError when the offset is negative" do
+ -> { "a".unpack1("C", offset: -1) }.should raise_error(ArgumentError)
+ end
+
+ it "returns nil if the offset is at the end of the string" do
+ "a".unpack1("C", offset: 1).should == nil
+ end
+
+ it "raises an ArgumentError when the offset is larget than the string" do
+ -> { "a".unpack1("C", offset: 2) }.should raise_error(ArgumentError)
+ end
+ end
end
diff --git a/test/ruby/test_pack.rb b/test/ruby/test_pack.rb
index c9ca9c3dfd4..af45adb2b23 100644
--- a/test/ruby/test_pack.rb
+++ b/test/ruby/test_pack.rb
@@ -869,4 +869,30 @@ EXPECTED
assert_equal "hogefuga", "aG9nZWZ1Z2E=".unpack1("m")
assert_equal "01000001", "A".unpack1("B*")
end
+
+ def test_unpack1_offset
+ assert_equal 65, "ZA".unpack1("C", offset: 1)
+ assert_equal "01000001", "YZA".unpack1("B*", offset: 2)
+ assert_nil "abc".unpack1("C", offset: 3)
+ assert_raise_with_message(ArgumentError, /offset can't be negative/) {
+ "a".unpack1("C", offset: -1)
+ }
+ assert_raise_with_message(ArgumentError, /offset outside of string/) {
+ "a".unpack1("C", offset: 2)
+ }
+ assert_nil "a".unpack1("C", offset: 1)
+ end
+
+ def test_unpack_offset
+ assert_equal [65], "ZA".unpack("C", offset: 1)
+ assert_equal ["01000001"], "YZA".unpack("B*", offset: 2)
+ assert_equal [nil, nil, nil], "abc".unpack("CCC", offset: 3)
+ assert_raise_with_message(ArgumentError, /offset can't be negative/) {
+ "a".unpack("C", offset: -1)
+ }
+ assert_raise_with_message(ArgumentError, /offset outside of string/) {
+ "a".unpack("C", offset: 2)
+ }
+ assert_equal [nil], "a".unpack("C", offset: 1)
+ end
end