Class: Sparkql::FunctionResolver

Inherits:
Object
  • Object
show all
Defined in:
lib/sparkql/function_resolver.rb

Overview

Binding class to all supported function calls in the parser. Current support requires that the resolution of function calls to happen on the fly at parsing time at which point a value and value type is required, just as literals would be returned to the expression tokenization level.

Name and argument requirements for the function should match the function declaration in SUPPORTED_FUNCTIONS which will run validation on the function syntax prior to execution.

Constant Summary collapse

SECONDS_IN_DAY = 
60 * 60 * 24
STRFTIME_DATE_FORMAT = 
'%Y-%m-%d'
STRFTIME_TIME_FORMAT = 
'%H:%M:%S.%N'
VALID_REGEX_FLAGS = 
["", "i"]
SUPPORTED_FUNCTIONS = 
{
  :polygon => {
    :args => [:character],
    :return_type => :shape
  }, 
  :rectangle => {
    :args => [:character],
    :return_type => :shape
  }, 
  :radius => {
    :args => [:character, [:decimal, :integer]],
    :return_type => :shape
  },
  :regex => {
    :args => [:character],
    :opt_args => [{
      :type => :character,
      :default => ''
    }],
    :return_type => :character
  },
  :tolower => {
    :args => [[:field, :character]],
    :resolve_for_type => true,
    :return_type => :character
  },
  :toupper => {
    :args => [[:field, :character]],
    :resolve_for_type => true,
    :return_type => :character
  },
  :startswith => {
    :args => [:character],
    :return_type => :startswith
  },
  :endswith => {
    :args => [:character],
    :return_type => :endswith
  },
  :contains => {
    :args => [:character],
    :return_type => :contains
  },
  :linestring => {
    :args => [:character],
    :return_type => :shape
  },
  :days => {
    :args => [:integer],
    :return_type => :datetime
  },
  :months => {
    :args => [:integer],
    :return_type => :datetime
  },
  :years => {
    :args => [:integer],
    :return_type => :datetime
  },
  :now => { 
    :args => [],
    :return_type => :datetime
  },
  :date => { 
    :args => [[:field,:datetime,:date]],
    :resolve_for_type => true,
    :return_type => :date
  },
  :time => { 
    :args => [[:field,:datetime,:date]],
    :resolve_for_type => true,
    :return_type => :time
  },
  :year => { 
    :args => [[:field,:datetime,:date]],
    :resolve_for_type => true,
    :return_type => :integer
  },
  :month => { 
    :args => [[:field,:datetime,:date]],
    :resolve_for_type => true,
    :return_type => :integer
  },
  :day => { 
    :args => [[:field,:datetime,:date]],
    :resolve_for_type => true,
    :return_type => :integer
  },
  :hour => { 
    :args => [[:field,:datetime,:date]],
    :resolve_for_type => true,
    :return_type => :integer
  },
  :minute => { 
    :args => [[:field,:datetime,:date]],
    :resolve_for_type => true,
    :return_type => :integer
  },
  :second => { 
    :args => [[:field,:datetime,:date]],
    :resolve_for_type => true,
    :return_type => :integer
  },
  :fractionalseconds => { 
    :args => [[:field,:datetime,:date]],
    :resolve_for_type => true,
    :return_type => :decimal
  },
  :range => {
    :args => [:character, :character],
    :return_type => :character
  },
  :wkt => {
    :args => [:character],
    :return_type => :shape
  }
}

Instance Method Summary collapse

Constructor Details

#initialize(name, args) ⇒ FunctionResolver

Construct a resolver instance for a function name: function name (String) args: array of literal hashes of the format :value=><escaped_literal_value>.

Empty arry for functions that have no arguments.



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# File 'lib/sparkql/function_resolver.rb', line 139

def initialize(name, args)
  @name = name
  @args = args
  @errors = []
end

Instance Method Details

#call ⇒ Object

Execute the function



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# File 'lib/sparkql/function_resolver.rb', line 194

def call()
  real_vals = @args.map { |i| i[:value]}
  name = @name.to_sym

  required_args = support[name][:args]
  total_args = required_args + Array(support[name][:opt_args]).collect {|args| args[:default]}
  fill_in_optional_args = total_args.drop(real_vals.length)

  fill_in_optional_args.each do |default|
    real_vals << default
  end
  method = name
  if support[name][:resolve_for_type]
    method_type =  @args.first[:type]
    method = "#{method}_#{method_type}"
  end
  v = self.send(method, *real_vals)

  unless v.nil? || v.key?(:function_name)
    v[:function_name] = @name
    v[:function_parameters] = real_vals
  end

  v
end

#errors ⇒ Object 



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# File 'lib/sparkql/function_resolver.rb', line 181

def errors
  @errors
end

#errors? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/sparkql/function_resolver.rb', line 185

def errors?
  @errors.size > 0
end

#return_type ⇒ Object 



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# File 'lib/sparkql/function_resolver.rb', line 177

def return_type
  support[@name.to_sym][:return_type]
end

#support ⇒ Object 



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# File 'lib/sparkql/function_resolver.rb', line 189

def support
  SUPPORTED_FUNCTIONS
end

#validate ⇒ Object

Validate the function instance prior to calling it. All validation failures will show up in the errors array.



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# File 'lib/sparkql/function_resolver.rb', line 147

def validate()
  name = @name.to_sym
  unless support.has_key?(name)
    @errors << Sparkql::ParserError.new(:token => @name, 
      :message => "Unsupported function call '#{@name}' for expression",
      :status => :fatal )
    return
  end

  required_args = support[name][:args]
  total_args = required_args + Array(support[name][:opt_args]).collect {|args| args[:type]}

  if @args.size < required_args.size || @args.size > total_args.size
    @errors << Sparkql::ParserError.new(:token => @name, 
      :message => "Function call '#{@name}' requires #{required_args.size} arguments",
      :status => :fatal )
    return
  end

  count = 0
  @args.each do |arg|
    unless Array(total_args[count]).include?(arg[:type])
      @errors << Sparkql::ParserError.new(:token => @name, 
        :message => "Function call '#{@name}' has an invalid argument at #{arg[:value]}",
        :status => :fatal )
    end
    count +=1
  end
end