Class: RSQL::EvalContext

Inherits:
Object
  • Object
show all
Defined in:
lib/rsql/eval_context.rb

Overview

This class wraps all dynamic evaluation and serves as the reflection class for adding methods dynamically.

Defined Under Namespace

Classes: Registration

Constant Summary collapse

HEXSTR_LIMIT = 
32

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(options = OpenStruct.new) ⇒ EvalContext

Returns a new instance of EvalContext.



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# File 'lib/rsql/eval_context.rb', line 42

def initialize(options=OpenStruct.new)
    @opts         = options
    @prompt       = nil
    @verbose      = @opts.verbose
    @hexstr_limit = HEXSTR_LIMIT
    @results      = nil

    @loaded_fns         = []
    @loaded_fns_state   = {}
    @init_registrations = []
    @bangs              = {}
    @global_bangs       = {}

    @registrations = {
        :version => Registration.new('version', [], {},
            method(:version),
            'version',
            'Version information about RSQL, the client, and the server.'),
        :help => Registration.new('help', [], {},
            method(:help),
            'help',
            'Show short syntax help.'),
        :grep => Registration.new('grep', [], {},
            method(:grep),
            'grep',
            'Show results when regular expression matches any part of the content.'),
        :reload => Registration.new('reload', [], {},
            method(:reload),
            'reload',
            'Reload the rsqlrc file.'),
        :desc => Registration.new('desc', [], {},
            method(:desc),
            'desc',
            'Describe the content of a recipe.'),
        :history => Registration.new('history', [], {},
            method(:history),
            'history(cnt=1)',
            'Print recent queries made (request a count or use :all for entire list).'),
        :set_max_rows => Registration.new('set_max_rows', [], {},
            Proc.new{|r| MySQLResults.max_rows = r},
            'set_max_rows',
            'Set the maximum number of rows to process.'),
        :max_rows => Registration.new('max_rows', [], {},
            Proc.new{MySQLResults.max_rows},
            'max_rows',
            'Get the maximum number of rows to process.'),
    }
end

Dynamic Method Handling

This class handles dynamic methods through the method_missing method

#method_missing(sym, *args, &block) ⇒ Object (private) 



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# File 'lib/rsql/eval_context.rb', line 721

def method_missing(sym, *args, &block)
    if reg = @registrations[sym]
        @bangs.merge!(reg.bangs)
        final_args = reg.args + args
        reg.block.call(*final_args)
    elsif MySQLResults.respond_to?(sym)
        MySQLResults.send(sym, *args)
    elsif MySQLResults.conn.respond_to?(sym)
        MySQLResults.conn.send(sym, *args)
    else
        super.method_missing(sym, *args, &block)
    end
end

Instance Attribute Details

#bangs ⇒ Object

Returns the value of attribute bangs.



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# File 'lib/rsql/eval_context.rb', line 92

def bangs
  @bangs
end

#prompt ⇒ Object (readonly)

Returns the value of attribute prompt.



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# File 'lib/rsql/eval_context.rb', line 91

def prompt
  @prompt
end

#verbose ⇒ Object

Returns the value of attribute verbose.



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# File 'lib/rsql/eval_context.rb', line 92

def verbose
  @verbose
end

Instance Method Details

#bang_eval(field, val) ⇒ Object 



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# File 'lib/rsql/eval_context.rb', line 160

def bang_eval(field, val)
    # allow individual bangs to override global ones, even if they're nil
    if @bangs.key?(field)
        bang = @bangs[field]
    else
        # todo: this will run on *every* value--this should be optimized
        # so that it's only run once on each query's result column
        # fields and then we'd know if any bangs are usable and pased in
        # for each result value
        @global_bangs.each do |m,b|
            if (String === m && m == field.to_s) ||
                (Regexp === m && m.match(field.to_s))
                bang = b
                break
            end
        end
    end

    if bang
        begin
            val = Thread.new{ eval("#{bang}(val)") }.value
        rescue Exception => ex
            if @verbose
                $stderr.puts("#{ex.class}: #{ex.message}", ex.backtrace)
            else
                $stderr.puts(ex.message, ex.backtrace.first)
            end
        end
    end

    return val
end

#call_init_registrations ⇒ Object 



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# File 'lib/rsql/eval_context.rb', line 94

def call_init_registrations
    @init_registrations.each do |sym|
        reg = @registrations[sym]
        sql = reg.block.call(*reg.args)
        query(sql) if String === sql
    end
end

#complete(str) ⇒ Object

Provide a list of tab completions given the prompted value.



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# File 'lib/rsql/eval_context.rb', line 256

def complete(str)
    if str[0] == ?.
        str.slice!(0)
        prefix = '.'
    else
        prefix = ''
    end

    ret  = MySQLResults.complete(str)

    ret += @registrations.keys.sort_by{|sym|sym.to_s}.collect do |sym|
        name = sym.to_s
        if name.start_with?(str)
            prefix + name
        else
            nil
        end
    end

    ret.compact!
    ret
end

#load(fn, opt = nil) ⇒ Object 



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# File 'lib/rsql/eval_context.rb', line 102

def load(fn, opt=nil)
    @loaded_fns << fn unless @loaded_fns_state.key?(fn)
    @loaded_fns_state[fn] = :loading

    # this should only be done after we have established a
    # mysql connection, so this option allows rsql to load the
    # init file immediately and then later make the init
    # registration calls--we set this as an instance variable
    # to allow for loaded files to call load again and yet
    # still maintain the skip logic
    if opt == :skip_init_registrations
        reset_skipping = @skipping_init_registrations = true
    end

    ret = Thread.new {
        begin
            eval(File.read(fn), binding, fn)
            nil
        rescue Exception => ex
            ex
        end
    }.value

    if Exception === ret
        @loaded_fns_state[fn] = :failed
        if @verbose
            $stderr.puts("#{ex.class}: #{ex.message}", ex.backtrace)
        else
            bt = ret.backtrace.collect{|line| line.start_with?(fn) ? line : nil}.compact
            $stderr.puts("#{ret.class}: #{ret.message}", bt, '')
        end
        ret = false
    else
        @loaded_fns_state[fn] = :loaded
        call_init_registrations unless @skipping_init_registrations
        ret = true
    end

    @skipping_init_registrations = false if reset_skipping

    return ret
end

#reload ⇒ Object 



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# File 'lib/rsql/eval_context.rb', line 145

def reload
    # some files may be loaded by other files, if so, we don't want to
    # reload them again here
    @loaded_fns.each{|fn| @loaded_fns_state[fn] = nil}
    @loaded_fns.each{|fn| self.load(fn, :skip_init_registrations) if @loaded_fns_state[fn] == nil}

    # load up the inits after all the normal registrations are ready
    call_init_registrations

    # report all the successfully loaded ones
    loaded = []
    @loaded_fns.each{|fn,state| loaded << fn if @loaded_fns_state[fn] == :loaded}
    puts "loaded: #{loaded.inspect}"
end

#reset_hexstr_limit ⇒ Object

Reset the hexstr limit back to the default value.



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# File 'lib/rsql/eval_context.rb', line 281

def reset_hexstr_limit
    @hexstr_limit = HEXSTR_LIMIT
end

#safe_eval(content, results, stdout) ⇒ Object

Safely evaluate Ruby content within our context.



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# File 'lib/rsql/eval_context.rb', line 195

def safe_eval(content, results, stdout)
    @results = results

    # allow a simple reload to be called directly as it requires a
    # little looser safety valve...
    if 'reload' == content
        reload
        return
    end

    # same relaxed call to load too
    if m = content.match(/^\s*load\s+'(.+)'\s*$/)
        self.load(m[1])
        return
    end

    # help out the poor user and fix up any describes
    # requested so they don't need to remember that it needs
    # to be a symbol passed in
    if m = content.match(/^\s*desc\s+([^:]\S+)\s*$/)
        content = "desc :#{m[1]}"
    end

    if stdout
        # capture stdout
        orig_stdout = $stdout
        $stdout = stdout
    end

    begin
        # in order to print out errors in a loaded script so
        # that we have file/line info, we need to rescue their
        # exceptions inside the evaluation
        th = Thread.new do
            eval('begin;' << content << %q{
              rescue Exception => ex
                if @verbose
                    $stderr.puts("#{ex.class}: #{ex.message}", ex.backtrace)
                else
                    bt = []
                    ex.backtrace.each do |t|
                      break if t.include?('bin/rsql')
                      bt << t unless t.include?('lib/rsql/') || t.include?('(eval)')
                    end
                    $stderr.puts(ex.message.gsub(/\(eval\):\d+:/,''),bt)
                end
              end
            })
        end
        value = th.value
    rescue Exception => ex
        $stderr.puts(ex.message.gsub(/\(eval\):\d+:/,''))
    ensure
        $stdout = orig_stdout if stdout
    end

    return value
end

#to_hexstr(bin, limit = @hexstr_limit, prefix = '0x') ⇒ Object

Convert a binary string value into a hexadecimal string.



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# File 'lib/rsql/eval_context.rb', line 287

def to_hexstr(bin, limit=@hexstr_limit, prefix='0x')
    return bin if bin.nil?

    cnt = 0
    str = prefix << bin.gsub(/./m) do |ch|
        if limit
            if limit < 1
                cnt += 1
                next
            end
            limit -= 1
        end
        '%02x' % ch.bytes.first
    end

    if limit && limit < 1 && 0 < cnt
        str << "... (#{cnt} bytes hidden)"
    end

    return str
end