Class: Ppr::Preprocessor

Inherits:
Object
  • Object
show all
Defined in:
lib/ppr/ppr_core.rb

Overview

Describes the ruby preprocessor.

Usage:

ppr = Ppr::Preprocessor.new(<some options>)
ppr.preprocess(<some input stream>, <some output stream>)

Instance Method Summary collapse

Constructor Details

#initialize(params = {}, apply: ".do", applyR: ".doR", define: ".def", defineR: ".defR", assign: ".assign", loadm: ".load", requirem: ".require", ifm: ".if", elsem: ".else", endifm: ".endif", endm: ".end", expand: ":<", separator: /^|[^\w]|$/, glue: "##", escape: "\\") ⇒ Preprocessor

Creates a new preprocessor, where apply, applyR, define, defineR, assign, loadm, requirem, ifm, elsem and endm are the keywords defining the beginings and end of a macro definitions, and where separator is the regular expression used for separating macro references to the remaining of the code, expand is the string representing the expansion operator of the macro, glue is string used for glueing a macro expension to the text, escape is the escape character.

Assigned parameters can be added through param to be used within the macros of the preprocessed text.



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# File 'lib/ppr/ppr_core.rb', line 386

def initialize(params = {},
               apply: ".do", applyR: ".doR", 
               define: ".def", defineR: ".defR",
               assign: ".assign",
               loadm: ".load", requirem: ".require",
               ifm: ".if", elsem: ".else", endifm: ".endif",
               endm: ".end",
               expand: ":<",
               separator: /^|[^\w]|$/, glue: "##",
               escape: "\\")
    # Check and Initialize the keywords
    # NOTE: since there are a lot of checks, use a generic but
    # harder to read code.
    keys = [ "apply", "applyR", "define", "defineR", "assign",
             "loadm", "requirem", "ifm", "elsem", "endifm", "endm"]
    # Sort the keywords by string content to quickly find erroneously
    # identical ones.
    keys.sort_by! {|key| eval(key) }
    # Check for identical keywords.
    keys.each_with_index do |key,i|
        value = eval(key)
        if i+1 < keys.size then
            # Check if the next keyword has the same string.
            nvalue = eval(keys[i+1])
            if value == nvalue then
                # Two keywords with same string.
                raise "'#{key}:#{value}' and '#{keys[i+1]}:#{nvalue}' keywords must be different."
            end
        end
    end

    # Seperate the begin of macro keywords from the others (they
    # are used differently).
    other_keys = ["elsem", "endifm", "endm"]
    begin_keys = keys - other_keys
    # Assign the begin of macro keywords to the corresponding attributes.
    begin_keys.each do |key|
        eval("@#{key} = #{key}.to_s")
    end
    # Generates the structures used for detecting the keywords.
    # For the begining of macros.
    @macro_keys = (begin_keys - other_keys).map do
        |key| self.instance_variable_get("@#{key}")
    end.sort!.reverse
    # For the other keywords.
    other_keys.each do |key|
        eval('@'+key+' = Regexp.new("^\s*#{Regexp.escape('+key+')}\s*$")')
    end

    # Sets the expand command.
    @expand = expand.to_s
    # Check and set the separator, the glue and the escape.
    @separator = Regexp.new("(?:#{separator}|#{glue})")
    @glue = glue.to_s

    # Initialize the current line number to 0.
    @number = LineNumber.new(0)
    # Initialize the macros.
    @macros = KeywordSearcher.new(@separator)

    # Initialize the stack for handling the if macros.
    @if_mode = []

    # Create the execution context for the macros.
    @generator = SaferGenerator.new
    @context = Object.new
    # Process the preprocessing parameters.
    params.each do |k,v|
        parameter_set(k,v)
    end
end

Instance Method Details

#apply_macros(line) ⇒ Object

Applies recursively each element of macros to line.

NOTE: a same macro is apply only once in a portion of the line.



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# File 'lib/ppr/ppr_core.rb', line 629

def apply_macros(line)
    # print "apply_macros on line=#{line}\n"

    # Initialize the expanded line.
    expanded = ""
    
    # Look for a first macro.
    macro,range = @macros.find(line)
    while macro do
        # print "macro.name=#{macro.name}, range=#{range}\n"
        # If the are some arguments, extract them and cut the macro
        # of the line.
        if range.first > 0 then
            sline = [ line[0..(range.first-1)] ] 
        else
            sline = [ "" ]
        end
        if line[range.last+1] == "(" then
            # print "Before line=#{line}\n"
            last = range.last+1 # Last character position of the arguments
            begin
                sline +=   
                each_argument_range(line,range.last+2).map do |arg_range|
                    last = arg_range.last
                    apply_macros(line[arg_range])
                end
            rescue Exception => e
                # A problem occurs while extracting the arguments.
                # Re-raise it after processing its message.
                raise e, macro.e_message(" " + e.message,@number)
            end
            range = range.first..(last+1)
        end
        if range.last + 1 < line.size then
            sline << line[(range.last+1)..-1]
        else
            sline << ""
        end
        # print "After sline=#{sline}\n"
        result = macro.apply(@number,*(sline[1..-2]))
        # print "Macro result=#{result}, sline[0]=#{sline[0]} sline[-1]=#{sline[-1]}\n"
        # Recurse on the modified portion of the line if the macro
        # requires it
        result = apply_macros(result) unless macro.final?
        # print "Final expansion result=#{result}\n"
        # Join the macro expansion result to the begining of the line
        # removing the possible glue string.
        expanded += unglue_back(sline[0]) + result
        # print "expanded = #{expanded}\n"
        # The remaining is to treat again after removing the possible
        # glue string
        line = unglue_front(sline[-1])
        # Look for the next macro
        macro,range = @macros.find(line)
    end
    # Add the remaining of the line to the expansion result.
    expanded += line
    # print "## expanded=#{expanded}\n"
    return expanded
end

#each_argument_range(line, start) ⇒ Object

Iterates over the range each argument of a line from offset start.

NOTE: keywords included into a longer one are ignored.



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# File 'lib/ppr/ppr_core.rb', line 516

def each_argument_range(line,start)
    return to_enum(:each_argument_range,line,start) unless block_given?
    begin
        # Get the next range
        range = get_argument_range(line,start)
        if range.last >= line.size then
            raise "invalid line for arguments: #{line}"
        end
        # Apply the block on the range.
        yield(range)
        # Prepares the next range.
        start = range.last + 2
    end while start > 0 and line[start-1] != ")"
end

#get_argument_range(line, start) ⇒ Object

Gets the range of an argument starting at offset start in line.



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# File 'lib/ppr/ppr_core.rb', line 505

def get_argument_range(line, start)
    if start >= line.size then
        raise "incomplete arguments in macro call."
    end
    range = line[start..-1].match(/(\\\)|\\,|[^\),])*/).offset(0)
    return (range[0]+start)..(range[1]+start-1)
end

#get_macro_def(line) ⇒ Object

Extract a macro definition from a line if there is one.



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# File 'lib/ppr/ppr_core.rb', line 548

def get_macro_def(line)
    line = line.strip
    # Locate and identify the macro keyword.
    macro_type = @macro_keys.find { |mdef| line.start_with?(mdef) }
    return nil unless macro_type
    line = line[(macro_type.size)..-1]
    if /^\w/.match(line) then
        # Actually the line was starting with a word including @define,
        # this is not a real macro definition.
        return nil
    end
    # Sets the flags according to the type.
    final = (macro_type == @define or macro_type == @apply) ? true : false
    named = (macro_type == @define or macro_type == @defineR or
             macro_type == @assign) ? true : false
    # Process the macro.
    line = line.strip
    if named then
        # Handle the case of named macros.
        # Extract the macro name.
        name = /[a-zA-Z_]\w*/.match(line).to_s
        if name.empty? then
            # Macro with no name, error.
            raise Macro.e_message(""," macro definition without name.",
                                  @number)
        end
        line = line[name.size..-1]
        line = line.strip
        # Extract the arguments if any
        # print "line=#{line}\n"
        par = /^\(\s*[a-zA-Z_]\w*\s*(,\s*[a-zA-Z_]\w*\s*)*\)/.match(line)
        if par then
            if macro_type == @assign then
                # Assignment macro: there should not be any argument.
                raise Macro.e_message(""," assignement with argument.",
                                      @number)
            end
            # There are arguments, process them.
            par = par.to_s
            # Extract them
            arguments = par.scan(/[a-zA-Z_]\w*/)
            line = line[par.size..-1].strip
        else
            # Check if there are some invalid arguments
            if line[0] == "(" then
                # Invalid arguments.
                raise Macro.e_message(name,
                        " invalid arguments for macro definition.", @number)
            end
            # No argument.
            arguments = []
        end
    else
        # Handle the case of unnamed macros.
        name = ""
    end
    case macro_type
    when @assign then
        macro = Assign.new(name,@number,self,expand: @expand)
    when @loadm then
        macro = Load.new(@number,self,expand: @expand)
    when @requirem then
        macro = Require.new(@number,self,expand: @expand)
    when @ifm then
        macro = If.new(@number,self,expand: @expand)
    else
        macro = Macro.new(name,@number,self,
                          *arguments,final: final,expand: @expand) 
    end
    # Is it a one-line macro?
    unless line.empty? then
        # Yes, adds the content to the macro.
        macro << line
    end
    return macro
end

#is_elsem?(line) ⇒ Boolean

Tells if a line corresponds to an else keyword.

Returns:

  • (Boolean) 


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# File 'lib/ppr/ppr_core.rb', line 538

def is_elsem?(line)
    @elsem.match(line)
end

#is_endifm?(line) ⇒ Boolean

Tells if a line corresponds to an endif keyword.

Returns:

  • (Boolean) 


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# File 'lib/ppr/ppr_core.rb', line 543

def is_endifm?(line)
    @endifm.match(line)
end

#is_endm?(line) ⇒ Boolean

Tells if a line corresponds to an end keyword.

Returns:

  • (Boolean) 


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# File 'lib/ppr/ppr_core.rb', line 533

def is_endm?(line)
    @endm.match(line)
end

#parameter_get(param) ⇒ Object

Gets the value of parameter +param.



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# File 'lib/ppr/ppr_core.rb', line 474

def parameter_get(param)
    return @context.instance_variable_get(Ppr.to_attribute(param))
end

#parameter_set(param, value) ⇒ Object

Sets parameter param to value.



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# File 'lib/ppr/ppr_core.rb', line 468

def parameter_set(param,value)
    # print "Setting #{Ppr.to_attribute(param)} with #{value.to_s}\n"
    @context.instance_variable_set(Ppr.to_attribute(param),value.to_s)
end

#preprocess(input, output) ⇒ Object

Preprocess an input stream and write the result to an output stream.



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# File 'lib/ppr/ppr_core.rb', line 732

def preprocess(input, output)
    # # The current list of macros.
    # @macros = KeywordSearcher.new(@separator)

    # The macro currently being input.
    cur_macro = nil

    # Process the input line by line
    input.each_line.with_index do |line,i|
        @number.set(i+1)
        # check if the line is to skip.
        if @if_mode[-1] == :skip_to_else then
            # Skipping until next else...
            if is_elsem?(line) then
                # And there is an else, enter in keep to endif mode.
                @if_mode[-1] = :keep_to_endif
            end
            next # Skip.
        elsif @if_mode[-1] == :keep_to_else then
            # Keeping until an else is met.
            if is_elsem?(line) then
                # And there is an else, enter in skip to endif mode.
                @if_mode[-1] = :skip_to_endif
                # And skip current line since it is a keyword.
                next
            elsif is_endifm?(line) then
                # This is the end of the if macro.
                @if_mode.pop
                # And skip current line since it is a keyword.
                next
            end
        elsif @if_mode[-1] == :skip_to_endif then
            # Skipping until next endif.
            if is_endifm?(line) then
                # And there is an endif, end the if macro.
                @if_mode.pop
            end
            next # Skip
        elsif @if_mode[-1] == :keep_to_endif then
            if is_endifm?(line)
            @if_mode.pop
                # And there is an endif, end the if macro.
                @if_mode.pop
                # And skip current line since it is a keyword.
                next
            end
        end
        # No skip.

        # Check if there are invalid elsem or endifm
        if is_elsem?(line) then
            raise Macro.e_message( "invalid #{@elsem} keyword.",@number)
        elsif is_endifm?(line) then
            raise Macro.e_message( "invalid #{@endifm} keyword.",@number)
        end

        # Is a macro being input?
        if cur_macro then
            # Yes.
            if get_macro_def(line) then
                # Yet, there is a begining of a macro definition: error
                raise cur_macro.e_message(
                  "cannot define a new macro within another macro.",@number)
            end
            # Is the current macro being closed?
            if is_endm?(line) then
                # Yes, close the macro.
                output << close_macro(cur_macro)
                # The macro ends here.
                cur_macro = nil
            else
                # No add the line to the current macro.
                cur_macro << line
            end
        else
            # There in no macro being input.
            # Check if a new macro definition is present.
            cur_macro = get_macro_def(line)
            if cur_macro and !cur_macro.empty? then
                # This is a one-line macro close it straight await.
                output << close_macro(cur_macro)
                # The macro ends here.
                cur_macro = nil
                next # The macro definition is not to be kept in the result
            end
            next if cur_macro # A new multi-line macro definition is found,
                              # it is not to be kept in the result.
            # Check if an end of multi-line macro defintion is present.
            if is_endm?(line) then
                # Not in a macro, so error.
                raise Macro.e_message("",
                    "#{@endm} outside a macro definition.",@number)
            end
            # Recursively apply the macro calls of the line.
            line = apply_macros(line)
            # Write the line to the output.
            # print ">#{line}"
            output << line
        end
    end
end

#run(&proc) ⇒ Object

Executes a macro in a safe context.



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# File 'lib/ppr/ppr_core.rb', line 461

def run(&proc)
    @generator.run do |__stream__|
        @context.instance_exec(__stream__,&proc) 
    end
end

#unglue_back(string) ⇒ Object

Restores a string whose ending may have been glued.



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# File 'lib/ppr/ppr_core.rb', line 493

def unglue_back(string)
    if string.end_with?(@glue) then
        # There is a glue, so remove it.
        string = string[0..(-@glue.size-1)] 
    elsif string.end_with?("\\") then
        # There is an escape, so remove it.
        string = string[0..-2]
    end
    return string
end

#unglue_front(string) ⇒ Object

Restores a string whose begining may have been glued.



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# File 'lib/ppr/ppr_core.rb', line 481

def unglue_front(string)
    if string.start_with?(@glue) then
        # There is a glue, so remove it.
        string = string[@glue.size..-1] 
    elsif string.start_with?("\\") then
        # There is an escape, so remove it.
        string = string[1..-1]
    end
    return string
end