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LibJS: Add String.prototype.lastIndexOf

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This commit is contained in:
Kesse Jones 2020-05-01 11:17:30 -03:00 • committed by Andreas Kling
parent 46b79eaad9
commit 6dbb5df81f
3 changed files with 62 additions and 0 deletions
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34
Libraries/LibJS/Runtime/StringPrototype.cpp
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@ -81,6 +81,7 @@ StringPrototype::StringPrototype()
put_native_function("substring", substring, 2, attr);
put_native_function("includes", includes, 1, attr);
put_native_function("slice", slice, 2, attr);
put_native_function("lastIndexOf", last_index_of, 1, attr);
}
StringPrototype::~StringPrototype()
@ -425,4 +426,37 @@ Value StringPrototype::slice(Interpreter& interpreter)
return js_string(interpreter, string_part);
}
Value StringPrototype::last_index_of(Interpreter& interpreter)
{
auto string = string_from(interpreter);
if (string.is_null())
return {};
if (interpreter.argument_count() == 0)
return Value(-1);
auto search_string = interpreter.argument(0).to_string();
if (search_string.length() > string.length())
return Value(-1);
ssize_t max_index = string.length() - search_string.length();
ssize_t from_index = max_index;
if (interpreter.argument_count() >= 2) {
from_index = static_cast<ssize_t>(interpreter.argument(1).to_i32());
if (from_index < 0)
from_index = 0;
if (from_index > max_index)
from_index = max_index;
}
for (ssize_t i = from_index; i >= 0; --i) {
auto part_view = string.substring_view(i, search_string.length());
if (part_view == search_string)
return Value((i32)i);
}
return Value(-1);
}
}

1
Libraries/LibJS/Runtime/StringPrototype.h
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@ -57,6 +57,7 @@ private:
static Value concat(Interpreter&);
static Value includes(Interpreter&);
static Value slice(Interpreter&);
static Value last_index_of(Interpreter&);
};
}