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require "../spec_helper"
include Parcom
# NOTE: WORK IN PROGRESS
alias JSONType = Nil \
| Bool \
| Int64 \
| Float64 \
| String \
| Array(JSONValue) \
| Hash(String, JSONValue)
struct JSONValue
property data : JSONType
def initialize(@data)
end
end
def json_null
Parser.token_sequence("null".chars).map_const(JSONValue.new(nil))
end
def json_bool
t = Parser.token_sequence("true".chars).map_const(true)
f = Parser.token_sequence("false".chars).map_const(false)
(t | f).map { |b| JSONValue.new(b) }
end
# Only standard decimal ints for now
#def json_number
# base_num = Parser(Char, Char).satisfy(&.ascii_number?).some.map do |cs|
# cs.join.to_i64
# end
# sign = Parser.token('-').map_const(-1).recover(1)
# (sign + base_num).map { |s, n| JSONValue.new(s.to_i64 * n) }
#end
def json_number
digits = Parser(Char, Char).satisfy(&.ascii_number?).many
sign = Parser.token('-').map_const(-1).recover(1)
point = Parser.token('.').optional
sign.and_then do |s|
digits.and_then do |front|
point.and_then do |p|
digits.and_then do |back|
if front.empty? && back.empty?
Parser(Char, JSONValue).flunk
else
x =
case
when front.empty? && !p.nil? # {[], '.', _} # 0 <= x < 1
"0.#{back.join}".to_f64
when back.empty? #{_, _, []} # whole number
front.join.to_i64
else #when !front.empty? && !p.nil? && !back.empty? # some other float
"#{front.join}.#{back.join}".to_f64
#else
# raise "json_number, Should be unreachable: #{front} #{p} #{back}"
end
x = x.to_i64 if x.is_a?(Float64) && (x % 1).zero?
Parser(Char, JSONValue).pure(JSONValue.new(x * s))
end
end
end
end
end
end
def json_string
q = Parser.token('"')
s_char = Parser(Char, Char).first_of([
Parser.token_sequence(['\\', '"']).map_const('"'),
Parser(Char, Char).satisfy(&.!=('"')),
])
(q >> s_char.many << q).map { |cs| JSONValue.new(cs.join) }
end
def ws
Parser(Char, Char).satisfy(&.whitespace?).many
end
def json_array
delim = ws >> Parser.token(',') >> ws
elements = json_value.sep_by(delim)
front = Parser.token('[') >> ws
back = ws >> Parser.token(']')
(front >> elements << back).map { |es| JSONValue.new(es) }
end
def json_value : Parser(Char, JSONValue)
Parser.first_of([
json_null,
json_bool,
json_number,
json_string,
json_array,
])
end
describe "example: JSON parsing" do
describe "json_null" do
it "parses the string 'null' and returns nil when successful" do
result = json_null.parse(Tokens.from_string("null"))
result.value.data.should be_nil
result.tokens.empty?.should be_true
expect_raises(ParserFail) { json_null.parse(Tokens.from_string("")) }
end
end
describe "json_bool" do
it "parses the strings 'true' or 'false' and returns bool" do
result = json_bool.parse(Tokens.from_string("true"))
result.value.data.should be_true
result.tokens.empty?.should be_true
result = json_bool.parse(Tokens.from_string("false"))
result.value.data.should be_false
result.tokens.empty?.should be_true
expect_raises(ParserFail) { json_bool.parse(Tokens.from_string("")) }
end
end
describe "json_number" do
it "parses positive and negative integers" do
{"42", "42.", "42.000000"}.each do |s|
result = json_number.parse(Tokens.from_string(s))
result.value.data.should eq(42)
result.value.data.should be_a(Int64)
result.tokens.empty?.should be_true
result = json_number.parse(Tokens.from_string("-#{s}"))
result.value.data.should eq(-42)
result.value.data.should be_a(Int64)
result.tokens.empty?.should be_true
end
end
it "parses positive and negative floats between -1 and 1" do
{"0.1234", ".1234", ".12340000"}.each do |s|
result = json_number.parse(Tokens.from_string(s))
result.value.data.should eq(0.1234)
result.value.data.should be_a(Float64)
result.tokens.empty?.should be_true
result = json_number.parse(Tokens.from_string("-#{s}"))
result.value.data.should eq(-0.1234)
result.value.data.should be_a(Float64)
result.tokens.empty?.should be_true
end
end
it "parses positive and negative floats with a whole-number component" do
{"12.34", "0012.3400"}.each do |s|
result = json_number.parse(Tokens.from_string(s))
result.value.data.should eq(12.34)
result.value.data.should be_a(Float64)
result.tokens.empty?.should be_true
result = json_number.parse(Tokens.from_string("-#{s}"))
result.value.data.should eq(-12.34)
result.value.data.should be_a(Float64)
result.tokens.empty?.should be_true
end
end
it "parses 0 as an int in various forms" do
{"0", "0.0", "0000", ".000", "000.", "-0", "-0.", "-.0", "-0.0"}.each do |s|
result = json_number.parse(Tokens.from_string(s))
result.value.data.should eq(0)
result.value.data.should be_a(Int64)
result.tokens.empty?.should be_true
end
end
it "does not parse '.' or '-.' as 0" do
expect_raises(ParserFail) { json_number.parse(Tokens.from_string(".")) }
end
it "fails when input if not a number" do
expect_raises(ParserFail) { json_number.parse(Tokens.from_string("")) }
expect_raises(ParserFail) { json_number.parse(Tokens.from_string("foo")) }
end
end
describe "json_string" do
it "can parse non-empty strings" do
result = json_string.parse(Tokens.from_string("\"foo\""))
result.value.data.should eq("foo")
result.tokens.empty?.should be_true
end
it "can parse empty strings" do
result = json_string.parse(Tokens.from_string("\"\""))
result.value.data.should eq("")
result.tokens.empty?.should be_true
end
it "can parse escaped quotes" do
result = json_string.parse(Tokens.from_string("\"escaped \\\"\\\" quotes\""))
result.value.data.should eq("escaped \"\" quotes")
result.tokens.empty?.should be_true
end
end
describe "json_value" do
it "parses null" do
result = json_value.parse(Tokens.from_string("null"))
result.value.data.should be_nil
result.tokens.empty?.should be_true
end
it "parses bools" do
result = json_value.parse(Tokens.from_string("true"))
result.value.data.should be_true
result.tokens.empty?.should be_true
result = json_value.parse(Tokens.from_string("false"))
result.value.data.should be_false
result.tokens.empty?.should be_true
end
it "parses ints" do
result = json_value.parse(Tokens.from_string("42"))
result.value.data.should eq(42)
result.value.data.should be_a(Int64)
result.tokens.empty?.should be_true
result = json_value.parse(Tokens.from_string("-42"))
result.value.data.should eq(-42)
result.value.data.should be_a(Int64)
result.tokens.empty?.should be_true
end
it "parses floats" do
result = json_value.parse(Tokens.from_string("12.34"))
result.value.data.should eq(12.34)
result.value.data.should be_a(Float64)
result.tokens.empty?.should be_true
result = json_value.parse(Tokens.from_string("-12.34"))
result.value.data.should eq(-12.34)
result.value.data.should be_a(Float64)
result.tokens.empty?.should be_true
end
it "parses strings" do
result = json_value.parse(Tokens.from_string("\"foo\""))
result.value.data.should eq("foo")
result.tokens.empty?.should be_true
end
end
end
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