Class: Yadriggy::Syntax

Inherits:
Object
  • Object
show all
Defined in:
lib/yadriggy/syntax.rb

Overview

Syntax checker.

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(ast) ⇒ Syntax

Returns a new instance of Syntax.

Parameters:

  • ast (ASTree) —

    the grammar rules.



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# File 'lib/yadriggy/syntax.rb', line 60

def initialize(ast)
  @error_loc = nil
  @error_msg = nil
  @debug = false
  @hash = {}
  update_hash(ast.tree.body)
end

Instance Attribute Details

#debug=(value) ⇒ Object (writeonly)

debugging mode is on if true.



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# File 'lib/yadriggy/syntax.rb', line 40

def debug=(value)
  @debug = value
end

#hash ⇒ Hash (readonly)

Returns the grammar rules.

Returns:

  • (Hash) —

    the grammar rules.



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# File 'lib/yadriggy/syntax.rb', line 37

def hash
  @hash
end

Class Method Details

.check_syntax(block) ⇒ Boolean

Checks the syntax of the grammar rules.

Parameters:

  • block (ASTnode) —

    the grammar rules.

Returns:

  • (Boolean) —

    false if a syntax error is found in the given grammar rules.



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# File 'lib/yadriggy/syntax.rb', line 49

def self.check_syntax(block)
  @syntax.nil? || @syntax.check(block)
end

.last_error ⇒ String

Returns the error message for the grammar rule last checked.

Returns:

  • (String) —

    the error message for the grammar rule last checked.



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# File 'lib/yadriggy/syntax.rb', line 55

def self.last_error
  @syntax.error
end

.ruby_syntax ⇒ Syntax

Defines Ruby syntax and returns its Syntax object.

Returns:

  • (Syntax) —

    the Ruby syntax.



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# File 'lib/yadriggy/syntax.rb', line 455

def self.ruby_syntax
  Yadriggy.define_syntax do
    expr  <= Name | Number | Super | Binary | Unary | SymbolLiteral |
            ConstPathRef | StringLiteral | StringInterpolation |
            ArrayLiteral | Paren | Call | ArrayRef | HashLiteral |
            Return | ForLoop | Loop | Conditional | Break |
            Lambda | BeginEnd | Def | ModuleDef
    exprs <= Exprs | expr

    Name <= { name: String }
    Number     <= { value: Numeric }
    Super      <= {}
    Identifier <= Name
    SymbolLiteral    <= { name: String }
    VariableCall     <= Name
    InstanceVariable <= Name
    GlobalVariable   <= Name
    Label      <= Name
    Reserved   <= Name
    Const      <= Name
    Binary     <= { left: expr, op: Symbol, right: expr }
    ArrayRef   <= { array: expr, indexes: [ expr ] }
    ArrayRefField  <= ArrayRef
    Assign     <= Binary
    Dots       <= Binary
    Unary      <= { op: Symbol, operand: expr }
    ConstPathRef   <= { scope: (ConstPathRef | Const), name: Const }
    ConstPathField <= ConstPathRef
    StringLiteral  <= { value: String }
    StringInterpolation <= { contents: [ exprs ] }
    ArrayLiteral   <= { elements: [ expr ] }
    Paren      <= { expression: expr }
    HashLiteral    <= { pairs: [ expr * expr ] }
    Return     <= { values: [ expr ] }
    ForLoop    <= {vars: [ Identifier ], set: expr, body: exprs }
    Loop       <= { op: Symbol, cond: expr, body: exprs }
    Conditional <= { op: Symbol, cond: expr, then: exprs,
                     all_elsif: [expr * exprs], else: (exprs) }
    Parameters <= { params: [ Identifier ],
                   optionals: [ Identifier * expr ],
                   rest_of_params: (Identifier),
                   params_after_rest: [ Identifier ],
                   keywords: [ Label * expr ],
                   rest_of_keywords: (Identifier),
                   block_param: (Identifier) }
    Block      <= Parameters + { body: exprs }
    Lambda     <= Block
    Call       <= { receiver: (expr), op: (Symbol), name: Identifier,
                    args: [ expr ], block_arg: (expr), block: (Block) }
    Command    <= Call
    Exprs      <= { expressions: [ expr ] }
    Rescue     <= { types: [ Const | ConstPathRef ],
                    parameter: (Identifier),
                    body: (exprs), nested_rescue: (Rescue),
                    else: (exprs), ensure: (exprs) }
    BeginEnd   <= { body: exprs, rescue: (Rescue) }
    Def        <= Parameters +
                  { singular: (expr), name: Identifier, body: exprs,
                    rescue: (Rescue) }
    ModuleDef  <= { name: Const | ConstPathRef, body: exprs,
                    rescue: (Rescue) }
    ClassDef   <= ModuleDef +
                  { superclass: (Const | ConstPathRef) }
    SingularClassDef <= { name: expr, body: exprs,
                    rescue: (Rescue) }
    Program    <= { elements: exprs }
  end
end

Instance Method Details

#add_rules(syntax = nil) { ... } ⇒ Object

Adds rules.

Parameters:

  • syntax (Syntax) (defaults to: nil) —

    the rules of this given syntax are added. This parameter is optional.

Yields:

  • the rules in the block are added. The block is optional.



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# File 'lib/yadriggy/syntax.rb', line 89

def add_rules(syntax=nil, &block)
  if syntax.is_a?(Syntax)
    syntax.hash.each do |k,v|
      @hash[k] = v
    end
  elsif block.is_a?(Proc)
    ast = Yadriggy::reify(block)
    if Syntax.check_syntax(ast.tree)
      update_hash(ast.tree.body)
    else
      raise Syntax.last_error
    end
  end
end

#check(tree) ⇒ Boolean

Checks the syntax of the given AST.

Parameters:

Returns:

  • (Boolean) —

    true when the given AST is syntactically correct.



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# File 'lib/yadriggy/syntax.rb', line 118

def check(tree)
  error_cleared!
  expr = find_hash_entry(tree.class)
  if expr
    check_expr(expr, tree, false) || error_found!(tree, tree)
  else
    error_found!(tree, tree, "no rule for #{tree.class}")
  end
end

#check_error(astree) ⇒ void

This method returns an undefined value.

Checks the syntax of the given AST and raise an error if a syntax error is found.

Parameters:

Raises:



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# File 'lib/yadriggy/syntax.rb', line 110

def check_error(astree)
  raise_error unless check(astree.is_a?(ASTree) ? astree.tree : astree)
end

#check_usertype(user_type, tree) ⇒ Boolean

Checks whether the given AST matches the grammar rule for the given user type.

Parameters:

  • user_type (String|Symbol) —

    the name of the user type.

  • tree (ASTnode) —

    the AST.

Returns:

  • (Boolean) —

    true if the given AST matches.



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# File 'lib/yadriggy/syntax.rb', line 134

def check_usertype(user_type, tree)
  error_cleared!
  check_rule_usertype(user_type.to_s, tree, false)
end

#error ⇒ String

Returns an error message.

Returns:

  • (String) —

    an error message when the last invocation of #check returns false.



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# File 'lib/yadriggy/syntax.rb', line 142

def error
  if @error_loc.nil? && @error_msg.nil?
    ''
  else
    "#{@error_loc} DSL syntax error#{@error_msg}"
  end
end

#raise_error ⇒ Object

Raises a syntax-error exception.

Raises:



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# File 'lib/yadriggy/syntax.rb', line 152

def raise_error
  raise SyntaxError.new(error)
end

#update_hash(body) ⇒ void

This method returns an undefined value.

Parameters:

  • body (Body) 


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# File 'lib/yadriggy/syntax.rb', line 71

def update_hash(body)
  return if body.nil?

  if body.is_a?(Binary)
    key = to_hash_key(body.left)
    @hash[key] = body.right
  else
    body.expressions.each do |e|
      @hash[to_hash_key(e.left)] = e.right
    end
  end
end