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doctools::tcl::parse - Processing text in 'subst -novariables' format

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package require Tcl 8.4
package require snit
package require fileutil
package require logger
package require struct::list
package require struct::stack
package require struct::set
package require treeql
package require doctools::tcl::parse

::doctools::tcl::parse text tree text ?root?
::doctools::tcl::parse file tree path ?root?


This package provides commands for parsing text with embedded Tcl commands as accepted by the Tcl builtin command subst -novariables. The result of the parsing is an abstract syntax tree.

This is an internal package of doctools, for use by the higher level parsers processing the docidx, doctoc, and doctools markup languages.


Error format

When the parser encounters a problem in the input it will throw an error using the format described here.

  1. The message will contain the reason for the problem (unexpected character or end of input in input), the character in question, if any, and the line and column the problem was found at, in a human readable form. This part is not documented further as its format may change as we see fit. It is intended for human consumption, not machine.

  2. The error code however will contain a machine-readable representation of the problem, in the form of a 5-element list containing, in the order listed below

    1. the constant string doctools::tcl::parse
    2. the cause of the problem, one of

      - __char__
        Unexpected character in input
      - __eof__
        Unexpected end of the input
    3. The location of the problem as offset from the beginning of the input, counted in characters. Note: Line markers count as one character.

    4. The line the problem was found on (counted from 1 (one)),

    5. The column the problem was found at (counted from 0 (zero))

Tree Structure

After successfully parsing a string the generated tree will have the following structure:

  1. In the following items the word 'root' refers to the node which was specified as the root of the tree when invoking either text or file. This may be the actual root of the tree.

  2. All the following items further ignore the possibility of pre-existing attributes in the pre-existing nodes. If attributes exists with the same names as the attributes used by the parser the pre-existing values are written over. Attributes with names not clashing with the parser's attributes are not touched.

  3. The root node has no attributes.

  4. All other nodes have the attributes

    • type

      The value is a string from the set { Command , Text , Word }

    • range

      The value is either empty or a 2-element list containing integer numbers. The numbers are the offsets of the first and last character in the input text, of the token described by the node,.

    • line

      The value is an integer, it describes the line in the input the token described by the node ends on. Lines are counted from 1 (one).

    • col

      The value is an integer, it describes the column in the line in the input the token described by the node ends on. Columns are counted from 0 (zero).

  5. The children of the root, if any, are of type Command and Text, in semi-alternation. This means: After a Text node a Command node has to follow, and anything can follow a Command node, a Text or other Command node.

  6. The children of a Command node, if any, are of type Command, and Text, and Word, they describe the arguments of the command.

  7. The children of a Word node, if any, are of type Command, Text, in semi-alternation. This means: After a Text node a Command node has to follow, and anything can follow a Command node, a Text or other Command node.

  8. A Word node without children represents the empty string.

  9. All Text nodes are leaves of the tree.

  10. All leaves of the tree are either Text or Command nodes. Word nodes cannot be leaves.

Bugs, Ideas, Feedback

This document, and the package it describes, will undoubtedly contain bugs and other problems. Please report such in the category doctools of the Tcllib Trackers. Please also report any ideas for enhancements you may have for either package and/or documentation.

When proposing code changes, please provide unified diffs, i.e the output of diff -u.

Note further that attachments are strongly preferred over inlined patches. Attachments can be made by going to the Edit form of the ticket immediately after its creation, and then using the left-most button in the secondary navigation bar.


Tcl syntax, command, doctools, parser, subst, word


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Copyright © 2009 Andreas Kupries