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Original file line number | Diff line number | Diff line change |
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class SQLState | ||
attr_reader :state | ||
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def initialize(state = {}) | ||
@state = state | ||
end | ||
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def read_table_meta(table_name) | ||
@state[table_name] ? @state[table_name]['metadata'] || {} : {} | ||
end | ||
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def read_table_rows(table_name) | ||
@state[table_name] ? @state[table_name]['rows'] || [] : [] | ||
end | ||
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def read_information_schema | ||
@state.values.map { |data| data['metadata'] } | ||
end | ||
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def write_table_meta(table_name, data) | ||
@state[table_name] ||= {} | ||
@state[table_name]['metadata'] ||= {} | ||
@state[table_name]['metadata'].merge!(data) | ||
self.class.new(@state) | ||
end | ||
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def write_table_rows(table_name, data) | ||
@state[table_name] ||= {} | ||
@state[table_name]['rows'] ||= [] | ||
@state[table_name]['rows'] << data | ||
self.class.new(@state) | ||
end | ||
end | ||
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module SQLType | ||
def self.varchar(data) | ||
data.to_s.strip.sub(/^['"]/, '').sub(/['"]$/, '') | ||
end | ||
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def self.int(data) | ||
data.to_i | ||
end | ||
end | ||
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module SQLFunctions | ||
def self.create_table(state, *args, table_schema: 'public') | ||
output = [] | ||
table_name = args[2] | ||
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columns = {} | ||
columns_str = args[3..].join(' ').gsub(/[()]/, '').strip | ||
unless columns_str.empty? | ||
columns = Hash[columns_str.split(',').map { |column| column.strip.split(' ') }] | ||
end | ||
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if state.read_table_meta(table_name).empty? | ||
metadata = { | ||
'table_name' => table_name, | ||
'table_schema' => table_schema, | ||
'columns' => columns | ||
} | ||
state = state.write_table_meta(table_name, metadata) | ||
end | ||
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[output, state] | ||
end | ||
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def self.insert_into(state, *args) | ||
output = [] | ||
table_name = args[2] | ||
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sql_type_map = { | ||
'VARCHAR' => SQLType.method(:varchar), | ||
'INT' => SQLType.method(:int) | ||
} | ||
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values_index = args.index('VALUES') | ||
raise 'VALUES not found' if values_index.nil? | ||
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keys = args[3...values_index].join(' ').gsub(/[()]/, '').split(',').map(&:strip) | ||
values = args[values_index + 1..].join(' ').gsub(/[()]/, '').split(',').map(&:strip) | ||
key_value_map = Hash[keys.zip(values)] | ||
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metadata = state.read_table_meta(table_name) | ||
row = {} | ||
key_value_map.each do |key, value| | ||
row[key] = sql_type_map[metadata['columns'][key]].call(value) | ||
end | ||
state = state.write_table_rows(table_name, row) | ||
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[output, state] | ||
end | ||
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def self.select(state, *args) | ||
output = [] | ||
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from_index = args.index('FROM') | ||
# where_index = args.index('WHERE') | ||
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raise 'FROM not found' if from_index.nil? | ||
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select_keys = args[1...from_index].join(' ').split(',').map(&:strip) | ||
from_value = args[from_index + 1] | ||
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data = if from_value == 'information_schema.tables' | ||
state.read_information_schema | ||
else | ||
state.read_table_rows(from_value) | ||
end | ||
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data.each do |datum| | ||
output << select_keys.map { |key| [key, datum[key]] }.to_h | ||
end | ||
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[output, state] | ||
end | ||
end | ||
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def run_sql(input_sql) | ||
output = [] | ||
state = SQLState.new | ||
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input_sql = input_sql.map(&:strip).reject { |line| line.start_with?('--') } | ||
input_sql = input_sql.join(' ').split(';') | ||
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sql_function_map = { | ||
'CREATE TABLE' => SQLFunctions.method(:create_table), | ||
'SELECT' => SQLFunctions.method(:select), | ||
'INSERT INTO' => SQLFunctions.method(:insert_into) | ||
} | ||
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input_sql.each do |line| | ||
words = line.split(' ') | ||
words.each_index do |i| | ||
key = words[0..i].join(' ').strip | ||
if sql_function_map.key?(key) | ||
output, state = sql_function_map[key].call(state, *words.reject(&:empty?)) | ||
break | ||
end | ||
end | ||
end | ||
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[output.to_json] | ||
end |
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