me_util(n) [mojave man page]
grammar::me::util(n) Grammar operations and usage grammar::me::util(n) __________________________________________________________________________________________________________________________________________________ NAME
grammar::me::util - AST utilities SYNOPSIS
package require Tcl 8.4 package require grammar::me::util ?0.1? ::grammar::me::util::ast2tree ast tree ?root? ::grammar::me::util::ast2etree ast mcmd tree ?root? mcmd lc location mcmd tok from ?to? ::grammar::me::util::tree2ast tree ?root? _________________________________________________________________ DESCRIPTION
This package provides a number of utility command for the conversion between the various representations of abstract syntax trees as speci- fied in the document grammar::me_ast. ::grammar::me::util::ast2tree ast tree ?root? This command converts an ast from value to object representation. All nodes in the ast will be converted into nodes of this tree, with the root of the AST a child of the node root. If this node is not explicitly specified the root of the tree is used. Existing content of tree is not touched, i.e. neither removed nor changed, with the exception of the specified root node, which will gain a new child. ::grammar::me::util::ast2etree ast mcmd tree ?root? This command is like ::grammar::me::util::ast2tree, except that the result is in the extended object representation of the input AST. The source of the extended information is the command prefix mcmd. It has to understand two methods, lc, and tok, with the semantics specified below. mcmd lc location Takes the location of a token given as offset in the input stream and return a 2-element list containing the associated line number and column index, in this order. mcmd tok from ?to? Takes one or two locations from and to as offset in the input stream and returns a Tcl list containing the specified part of the input stream. Both location are inclusive. If to is not specified it will default to the value of from. Each element of the returned list is a list containing the token, its associated lexeme, the line number, and column index, in this order. Both the ensemble command ::grammar::me::tcl provided by the package grammar::me::tcl and the objects command created by the package ::grammar::me::cpu fit the above specification. ::grammar::me::util::tree2ast tree ?root? This command converts an ast in (extended) object representation into a value and returns it. If a root node is specified the AST is generated from that node downward. Otherwise the root of the tree object is used as the starting point. BUGS, IDEAS, FEEDBACK This document, and the package it describes, will undoubtedly contain bugs and other problems. Please report such in the category gram- mar_me of the Tcllib SF Trackers [http://sourceforge.net/tracker/?group_id=12883]. Please also report any ideas for enhancements you may have for either package and/or documentation. KEYWORDS
abstract syntax tree, syntax tree, tree CATEGORY
Grammars and finite automata COPYRIGHT
Copyright (c) 2005 Andreas Kupries <andreas_kupries@users.sourceforge.net> grammar_me 0.1 grammar::me::util(n)
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grammar::me_ast(n) Grammar operations and usage grammar::me_ast(n) __________________________________________________________________________________________________________________________________________________ NAME
grammar::me_ast - Various representations of ASTs DESCRIPTION
This document specifies various representations for the abstract syntax trees (short AST) generated by instances of ME virtual machines, independent of variant. Please go and read the document grammar::me_intro first if you do not know what a ME virtual machine is. ASTs and all the representations we specify distinguish between two types of nodes, namely: Terminal Terminal nodes refer to the terminal symbols found in the token stream. They are always leaf nodes. I.e. terminal nodes never have children. Nonterminal Nonterminal nodes represent a nonterminal symbol of the grammar used during parsing. They can occur as leaf and inner nodes of the tree. Both types of nodes carry basic range information telling a user which parts of the input are covered by the node by providing the location of the first and last tokens found within the range. Locations are provided as non-negative integer offsets from the beginning of the token stream, with the first token found in the stream located at offset 0 (zero). The root of an AS tree can be either a terminal or nonterminal node. AST VALUES
This representation of ASTs is a Tcl list. The main list represents the root node of the tree, with the representations of the children nested within. Each node is represented by a single Tcl list containing three or more elements. The first element is either the empty string or the name of a nonterminal symbol (which is never the empty string). The second and third elements are then the locations of the first and last tokens. Any additional elements after the third are then the representations of the children, with the leftmost child first, i.e. as the fourth element of the list representing the node. AST OBJECTS
In this representation an AST is represented by a Tcl object command whose API is compatible to the tree objects provided by the package struct::tree. I.e it has to support at least all of the methods described by that package, and may support more. Because of this the remainder of the specifications is written using the terms of struct::tree. Each node of the AST directly maps to a node in the tree object. All data beyond the child nodes, i.e. node type and input locations, are stored in attributes of the node in the tree object. They are: type The type of the AST node. The recognized values are terminal and nonterminal. range The locations of the first and last token of the terminal data in the input covered by the node. This is a list containing two loca- tions. detail This attribute is present only for nonterminal nodes. It contains the name of the nonterminal symbol stored in the node. EXTENDED AST OBJECTS
Extended AST objects are like AST objects, with additional information. detail This attribute is now present at all nodes. Its contents are unchanged for nonterminal nodes. For terminal nodes it contains a list describing all tokens from the input which are covered by the node. Each element of the list contains the token name, the associated lexeme attribute, line number, and column index, in this order. range_lc This new attribute is defined for all nodes, and contains the locations from attribute range translated into line number and column index. Lines are counted from 1, columns are counted from 0. BUGS, IDEAS, FEEDBACK This document, and the package it describes, will undoubtedly contain bugs and other problems. Please report such in the category gram- mar_me of the Tcllib SF Trackers [http://sourceforge.net/tracker/?group_id=12883]. Please also report any ideas for enhancements you may have for either package and/or documentation. KEYWORDS
AST, abstract syntax tree CATEGORY
Grammars and finite automata COPYRIGHT
Copyright (c) 2005 Andreas Kupries <andreas_kupries@users.sourceforge.net> grammar_me 0.1 grammar::me_ast(n)