reader_peg.tcl

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/*  -*- tcl -*- */
/*  -- $Id: reader_peg.tcl,v 1.1 2005/09/28 04:51:22 andreas_kupries Exp $ ---*/
/* */
/*  PAGE plugin - reader - PEG ~ Parsing Expression Grammar*/
/* */

/*  ### ### ### ######### ######### #########*/
/*  Imported API*/

/*  -----------------+--*/
/*  page_read        | Access to the input stream.*/
/*  page_read_done   |*/
/*  page_eof         |*/
/*  -----------------+--*/
/*  page_info        | Reporting to the user.*/
/*  page_warning     |*/
/*  page_error       |*/
/*  -----------------+--*/
/*  page_log_error   | Reporting of internals.*/
/*  page_log_warning |*/
/*  page_log_info    |*/
/*  -----------------+--*/

/*  ### ### ### ######### ######### #########*/
/*  Exported API*/

/*  -----------------+--*/
/*  page_rfeature    | Query for special plugin features page might wish to use.*/
/*  page_rtime       | Activate collection of timing statistics.*/
/*  page_rgettime    | Return the collected timing statistics.*/
/*  page_rlabel      | User readable label for the plugin.*/
/*  page_rhelp       | Doctools help text for plugin.*/
/*  page_roptions    | Options understood by plugin.*/
/*  page_rconfigure  | Option (re)configuration.*/
/*  page_rdata       | External access to processed input stream.*/
/*  page_rrun        | Process input stream per plugin configuration and hardwiring.*/
/*  -----------------+--*/

/*  ### ### ### ######### ######### #########*/
/*  Requisites*/

package require page::util::norm::peg ; /*  Normalize AST generated by reader of PEG grammars*/
package require page::parse::peg      ; /*  Mengine based parser for PE grammars.*/
package require struct::tree          ; /*  Data structure.*/
package require grammar::me::util     ; /*  AST conversion*/

global usec
global timed
    timed =  0

global cline
global ccol

/*  ### ### ### ######### ######### #########*/
/*  Implementation of exported API*/

ret  page_rlabel () {
    return {Parsing Expression Grammar}
}

ret  page_rfeature (type key) {
    return [string eq $key timeable]
}

ret  page_rtime () {
    global timed
    set    timed 1
    return
}

ret  page_rgettime () {
    global  usec
    return $usec
}

ret  page_rhelp () {
    return {}
}

ret  page_roptions () {
    return {}
}

ret  page_rconfigure (type option , type value) {
    return -code error "Cannot set value of unknown option \"$option\""
}

/*  proc page_rdata {} {}*/
/*  Created in 'Initialize'*/

ret  page_rrun () {
    global timed usec cline ccol
    page_log_info "reader/peg/run/parse"

    set ast {}
    set err {}

    # Location of the next character to be read.
    set cline 1
    set ccol  0

    if {$timed} {
    set usec [lindex [time {
        set ok [::page::parse::peg::parse ::Next err ast]
    }] 0] ; #{}
    } else {
    set ok [::page::parse::peg::parse ::Next err ast]
    }
    page_read_done
    page_log_info "reader/peg/run/check-for-errors"

    if {!$ok} {
    foreach {olc   messages} $err     break
    foreach {offset linecol} $olc     break
    foreach {line       col} $linecol break

    set olc [string map {{ } _} \
        [format %5d $line]]@[string map {{ } _} \
        [format %3d $col]]/([format %5d $offset])

    foreach m $messages {
        page_log_error "reader/peg/run: $olc: $m"
        page_error $m $linecol
    }

    page_log_info "reader/peg/run/failed"
    return {}
    }

    page_log_info "reader/peg/run/ast-conversion"

    struct::tree                        ::tree
    ::grammar::me::util::ast2etree $ast ::grammar::me::tcl ::tree
    ::page::util::norm::peg             ::tree

    set ast [::tree serialize]
    ::tree destroy

    page_log_info "reader/peg/run/ok"
    return $ast
}

/*  ### ### ### ######### ######### #########*/
/*  Internal helper code.*/

ret  Next () {
    global cline ccol

    if {[page_eof]} {return {}}

    set ch [page_read 1]

    if {$ch eq ""} {return {}}

    set tok [list $ch {} $cline $ccol]

    if {$ch eq "\n"} {
    incr cline ; set ccol 0
    } else {
    incr ccol
    }

    return $tok
}

/*  ### ### ### ######### ######### #########*/
/*  Initialization*/

package provide page::reader::peg 0.1