Programs/ctb_external.c - brltty - Git at Google

 /*
  * BRLTTY - A background process providing access to the console screen (when in
  *          text mode) for a blind person using a refreshable braille display.
  *
  * Copyright (C) 1995-2023 by The BRLTTY Developers.
  *
  * BRLTTY comes with ABSOLUTELY NO WARRANTY.
  *
  * This is free software, placed under the terms of the
  * GNU Lesser General Public License, as published by the Free Software
  * Foundation; either version 2.1 of the License, or (at your option) any
  * later version. Please see the file LICENSE-LGPL for details.
  *
  * Web Page: http://brltty.app/
  *
  * This software is maintained by Dave Mielke <dave@mielke.cc>.
  */

 #include "prologue.h"

 #include <string.h>
 #include <errno.h>

 #include "log.h"
 #include "ctb_translate.h"
 #include "brl_dots.h"
 #include "file.h"
 #include "parse.h"
 #include "utf8.h"

 static int
 putExternalRequests (BrailleContractionData *bcd) {
   typedef enum {
     REQ_TEXT,
     REQ_NUMBER
   } ExternalRequestType;

   typedef struct {
     const char *name;
     ExternalRequestType type;

     union {
       struct {
         const wchar_t *start;
         size_t count;
       } text;

       unsigned int number;
     } value;
   } ExternalRequestEntry;

   const ExternalRequestEntry externalRequestTable[] = {
     { .name = "cursor-position",
       .type = REQ_NUMBER,
       .value.number = bcd->input.cursor? bcd->input.cursor-bcd->input.begin+1: 0
     },

     { .name = "expand-current-word",
       .type = REQ_NUMBER,
       .value.number = prefs.expandCurrentWord
     },

     { .name = "capitalization-mode",
       .type = REQ_NUMBER,
       .value.number = prefs.capitalizationMode
     },

     { .name = "maximum-length",
       .type = REQ_NUMBER,
       .value.number = getOutputCount(bcd)
     },

     { .name = "text",
       .type = REQ_TEXT,
       .value.text = {
         .start = bcd->input.begin,
         .count = getInputCount(bcd)
       }
     },

     { .name = NULL }
   };

   FILE *stream = bcd->table->data.external.standardInput;
   const ExternalRequestEntry *req = externalRequestTable;

   while (req->name) {
     if (fputs(req->name, stream) == EOF) goto outputError;
     if (fputc('=', stream) == EOF) goto outputError;

     switch (req->type) {
       case REQ_TEXT: {
         const wchar_t *character = req->value.text.start;
         const wchar_t *end = character + req->value.text.count;

         while (character < end) {
           Utf8Buffer utf8;
           size_t utfs = convertWcharToUtf8(*character++, utf8);

           if (!utfs) return 0;
           if (fputs(utf8, stream) == EOF) goto outputError;
         }

         break;
       }

       case REQ_NUMBER:
         if (fprintf(stream, "%u", req->value.number) == EOF) goto outputError;
         break;

       default:
         logMessage(LOG_WARNING, "unimplemented external contraction request property type: %s: %u (%s)", bcd->table->data.external.command, req->type, req->name);
         return 0;
     }

     if (fputc('\n', stream) == EOF) goto outputError;
     req += 1;
   }

   if (fflush(stream) == EOF) goto outputError;
   return 1;

 outputError:
   logMessage(LOG_WARNING, "external contraction output error: %s: %s", bcd->table->data.external.command, strerror(errno));
   return 0;
 }

 static const unsigned char brfTable[0X40] = {
   /* 0X20   */ 0,
   /* 0X21 ! */ BRL_DOT_2 | BRL_DOT_3 | BRL_DOT_4 | BRL_DOT_6,
   /* 0X22 " */ BRL_DOT_5,
   /* 0X23 # */ BRL_DOT_3 | BRL_DOT_4 | BRL_DOT_5 | BRL_DOT_6,
   /* 0X24 $ */ BRL_DOT_1 | BRL_DOT_2 | BRL_DOT_4 | BRL_DOT_6,
   /* 0X25 % */ BRL_DOT_1 | BRL_DOT_4 | BRL_DOT_6,
   /* 0X26 & */ BRL_DOT_1 | BRL_DOT_2 | BRL_DOT_3 | BRL_DOT_4 | BRL_DOT_6,
   /* 0X27 ' */ BRL_DOT_3,
   /* 0X28 ( */ BRL_DOT_1 | BRL_DOT_2 | BRL_DOT_3 | BRL_DOT_5 | BRL_DOT_6,
   /* 0X29 ) */ BRL_DOT_2 | BRL_DOT_3 | BRL_DOT_4 | BRL_DOT_5 | BRL_DOT_6,
   /* 0X2A * */ BRL_DOT_1 | BRL_DOT_6,
   /* 0X2B + */ BRL_DOT_3 | BRL_DOT_4 | BRL_DOT_6,
   /* 0X2C , */ BRL_DOT_6,
   /* 0X2D - */ BRL_DOT_3 | BRL_DOT_6,
   /* 0X2E . */ BRL_DOT_4 | BRL_DOT_6,
   /* 0X2F / */ BRL_DOT_3 | BRL_DOT_4,
   /* 0X30 0 */ BRL_DOT_3 | BRL_DOT_5 | BRL_DOT_6,
   /* 0X31 1 */ BRL_DOT_2,
   /* 0X32 2 */ BRL_DOT_2 | BRL_DOT_3,
   /* 0X33 3 */ BRL_DOT_2 | BRL_DOT_5,
   /* 0X34 4 */ BRL_DOT_2 | BRL_DOT_5 | BRL_DOT_6,
   /* 0X35 5 */ BRL_DOT_2 | BRL_DOT_6,
   /* 0X36 6 */ BRL_DOT_2 | BRL_DOT_3 | BRL_DOT_5,
   /* 0X37 7 */ BRL_DOT_2 | BRL_DOT_3 | BRL_DOT_5 | BRL_DOT_6,
   /* 0X38 8 */ BRL_DOT_2 | BRL_DOT_3 | BRL_DOT_6,
   /* 0X39 9 */ BRL_DOT_3 | BRL_DOT_5,
   /* 0X3A : */ BRL_DOT_1 | BRL_DOT_5 | BRL_DOT_6,
   /* 0X3B ; */ BRL_DOT_5 | BRL_DOT_6,
   /* 0X3C < */ BRL_DOT_1 | BRL_DOT_2 | BRL_DOT_6,
   /* 0X3D = */ BRL_DOT_1 | BRL_DOT_2 | BRL_DOT_3 | BRL_DOT_4 | BRL_DOT_5 | BRL_DOT_6,
   /* 0X3E > */ BRL_DOT_3 | BRL_DOT_4 | BRL_DOT_5,
   /* 0X3F ? */ BRL_DOT_1 | BRL_DOT_4 | BRL_DOT_5 | BRL_DOT_6,
   /* 0X40 @ */ BRL_DOT_4,
   /* 0X41 A */ BRL_DOT_1,
   /* 0X42 B */ BRL_DOT_1 | BRL_DOT_2,
   /* 0X43 C */ BRL_DOT_1 | BRL_DOT_4,
   /* 0X44 D */ BRL_DOT_1 | BRL_DOT_4 | BRL_DOT_5,
   /* 0X45 E */ BRL_DOT_1 | BRL_DOT_5,
   /* 0X46 F */ BRL_DOT_1 | BRL_DOT_2 | BRL_DOT_4,
   /* 0X47 G */ BRL_DOT_1 | BRL_DOT_2 | BRL_DOT_4 | BRL_DOT_5,
   /* 0X48 H */ BRL_DOT_1 | BRL_DOT_2 | BRL_DOT_5,
   /* 0X49 I */ BRL_DOT_2 | BRL_DOT_4,
   /* 0X4A J */ BRL_DOT_2 | BRL_DOT_4 | BRL_DOT_5,
   /* 0X4B K */  BRL_DOT_1 | BRL_DOT_3,
   /* 0X4C L */ BRL_DOT_1 | BRL_DOT_2 | BRL_DOT_3,
   /* 0X4D M */ BRL_DOT_1 | BRL_DOT_3 | BRL_DOT_4,
   /* 0X4E N */ BRL_DOT_1 | BRL_DOT_3 | BRL_DOT_4 | BRL_DOT_5,
   /* 0X4F O */ BRL_DOT_1 | BRL_DOT_3 | BRL_DOT_5,
   /* 0X50 P */ BRL_DOT_1 | BRL_DOT_2 | BRL_DOT_3 | BRL_DOT_4,
   /* 0X51 Q */ BRL_DOT_1 | BRL_DOT_2 | BRL_DOT_3 | BRL_DOT_4 | BRL_DOT_5,
   /* 0X52 R */ BRL_DOT_1 | BRL_DOT_2 | BRL_DOT_3 | BRL_DOT_5,
   /* 0X53 S */ BRL_DOT_2 | BRL_DOT_3 | BRL_DOT_4,
   /* 0X54 T */ BRL_DOT_2 | BRL_DOT_3 | BRL_DOT_4 | BRL_DOT_5,
   /* 0X55 U */ BRL_DOT_1 | BRL_DOT_3 | BRL_DOT_6,
   /* 0X56 V */ BRL_DOT_1 | BRL_DOT_2 | BRL_DOT_3 | BRL_DOT_6,
   /* 0X57 W */ BRL_DOT_2 | BRL_DOT_4 | BRL_DOT_5 | BRL_DOT_6,
   /* 0X58 X */ BRL_DOT_1 | BRL_DOT_3 | BRL_DOT_4 | BRL_DOT_6,
   /* 0X59 Y */ BRL_DOT_1 | BRL_DOT_3 | BRL_DOT_4 | BRL_DOT_5 | BRL_DOT_6,
   /* 0X5A Z */ BRL_DOT_1 | BRL_DOT_3 | BRL_DOT_5 | BRL_DOT_6,
   /* 0X5B [ */ BRL_DOT_2 | BRL_DOT_4 | BRL_DOT_6,
   /* 0X5C \ */ BRL_DOT_1 | BRL_DOT_2 | BRL_DOT_5 | BRL_DOT_6,
   /* 0X5D ] */ BRL_DOT_1 | BRL_DOT_2 | BRL_DOT_4 | BRL_DOT_5 | BRL_DOT_6,
   /* 0X5E ^ */ BRL_DOT_4 | BRL_DOT_5,
   /* 0X5F _ */ BRL_DOT_4 | BRL_DOT_5 | BRL_DOT_6
 };

 static int
 handleExternalResponse_brf (BrailleContractionData *bcd, const char *value) {
   int useDot7 = prefs.capitalizationMode == CTB_CAP_DOT7;

   while (*value && (bcd->output.current < bcd->output.end)) {
     unsigned char brf = *value++ & 0XFF;
     unsigned char dots = 0;
     unsigned char superimpose = 0;

     if ((brf >= 0X60) && (brf <= 0X7F)) {
       brf -= 0X20;
     } else if ((brf >= 0X41) && (brf <= 0X5A)) {
       if (useDot7) superimpose |= BRL_DOT_7;
     }

     if ((brf >= 0X20) && (brf <= 0X5F)) dots = brfTable[brf - 0X20] | superimpose;
     *bcd->output.current++ = dots;
   }

   return 1;
 }

 static int
 handleExternalResponse_consumedLength (BrailleContractionData *bcd, const char *value) {
   int length;

   if (!isInteger(&length, value)) return 0;
   if (length < 1) return 0;
   if (length > getInputCount(bcd)) return 0;

   bcd->input.current = bcd->input.begin + length;
   return 1;
 }

 static int
 handleExternalResponse_outputOffsets (BrailleContractionData *bcd, const char *value) {
   if (bcd->input.offsets) {
     int previous = CTB_NO_OFFSET;
     unsigned int count = getInputCount(bcd);
     unsigned int index = 0;

     while (*value && (index < count)) {
       int offset;

       {
         char *delimiter = strchr(value, ',');

         if (delimiter) {
           int ok;

           {
             char oldDelimiter = *delimiter;
             *delimiter = 0;
             ok = isInteger(&offset, value);
             *delimiter = oldDelimiter;
           }

           if (!ok) return 0;
           value = delimiter + 1;
         } else if (isInteger(&offset, value)) {
           value += strlen(value);
         } else {
           return 0;
         }
       }

       if (offset < ((index == 0)? 0: previous)) return 0;
       if (offset >= getOutputCount(bcd)) return 0;

       bcd->input.offsets[index++] = (offset == previous)? CTB_NO_OFFSET: offset;
       previous = offset;
     }
   }

   return 1;
 }

 typedef struct {
   const char *name;
   int (*handler) (BrailleContractionData *bcd, const char *value);
   unsigned stop:1;
 } ExternalResponseEntry;

 static const ExternalResponseEntry externalResponseTable[] = {
   { .name = "brf",
     .stop = 1,
     .handler = handleExternalResponse_brf
   },

   { .name = "consumed-length",
     .handler = handleExternalResponse_consumedLength
   },

   { .name = "output-offsets",
     .handler = handleExternalResponse_outputOffsets
   },

   { .name = NULL }
 };

 static int
 getExternalResponses (BrailleContractionData *bcd) {
   FILE *stream = bcd->table->data.external.standardOutput;

   while (readLine(stream, &bcd->table->data.external.input.buffer, &bcd->table->data.external.input.size, NULL)) {
     int ok = 0;
     int stop = 0;
     char *delimiter = strchr(bcd->table->data.external.input.buffer, '=');

     if (delimiter) {
       const char *value = delimiter + 1;
       const ExternalResponseEntry *rsp = externalResponseTable;

       char oldDelimiter = *delimiter;
       *delimiter = 0;

       while (rsp->name) {
         if (strcmp(bcd->table->data.external.input.buffer, rsp->name) == 0) {
           if (rsp->handler(bcd, value)) ok = 1;
           if (rsp->stop) stop = 1;
           break;
         }

         rsp += 1;
       }

       *delimiter = oldDelimiter;
     }

     if (!ok) logMessage(LOG_WARNING, "unexpected external contraction response: %s: %s", bcd->table->data.external.command, bcd->table->data.external.input.buffer);
     if (stop) return 1;
   }

   logMessage(LOG_WARNING, "incomplete external contraction response: %s", bcd->table->data.external.command);
   return 0;
 }

 static int
 contractText_external (BrailleContractionData *bcd) {
   setOffset(bcd);
   while (++bcd->input.current < bcd->input.end) clearOffset(bcd);

   if (startContractionCommand(bcd->table)) {
     if (putExternalRequests(bcd)) {
       if (getExternalResponses(bcd)) {
         return 1;
       }
     }
   }

   stopContractionCommand(bcd->table);
   return 0;
 }

 static void
 finishCharacterEntry_external (BrailleContractionData *bcd, CharacterEntry *entry) {
 }

 static const ContractionTableTranslationMethods externalTranslationMethods = {
   .contractText = contractText_external,
   .finishCharacterEntry = finishCharacterEntry_external
 };

 const ContractionTableTranslationMethods *
 getContractionTableTranslationMethods_external (void) {
   return &externalTranslationMethods;
 }
	/*
	* BRLTTY - A background process providing access to the console screen (when in
	* text mode) for a blind person using a refreshable braille display.
	*
	* Copyright (C) 1995-2023 by The BRLTTY Developers.
	*
	* BRLTTY comes with ABSOLUTELY NO WARRANTY.
	*
	* This is free software, placed under the terms of the
	* GNU Lesser General Public License, as published by the Free Software
	* Foundation; either version 2.1 of the License, or (at your option) any
	* later version. Please see the file LICENSE-LGPL for details.
	*
	* Web Page: http://brltty.app/
	*
	* This software is maintained by Dave Mielke <dave@mielke.cc>.
	*/

	#include "prologue.h"

	#include <string.h>
	#include <errno.h>

	#include "log.h"
	#include "ctb_translate.h"
	#include "brl_dots.h"
	#include "file.h"
	#include "parse.h"
	#include "utf8.h"

	static int
	putExternalRequests (BrailleContractionData *bcd) {
	typedef enum {
	REQ_TEXT,
	REQ_NUMBER
	} ExternalRequestType;

	typedef struct {
	const char *name;
	ExternalRequestType type;

	union {
	struct {
	const wchar_t *start;
	size_t count;
	} text;

	unsigned int number;
	} value;
	} ExternalRequestEntry;

	const ExternalRequestEntry externalRequestTable[] = {
	{ .name = "cursor-position",
	.type = REQ_NUMBER,
	.value.number = bcd->input.cursor? bcd->input.cursor-bcd->input.begin+1: 0
	},

	{ .name = "expand-current-word",
	.type = REQ_NUMBER,
	.value.number = prefs.expandCurrentWord
	},

	{ .name = "capitalization-mode",
	.type = REQ_NUMBER,
	.value.number = prefs.capitalizationMode
	},

	{ .name = "maximum-length",
	.type = REQ_NUMBER,
	.value.number = getOutputCount(bcd)
	},

	{ .name = "text",
	.type = REQ_TEXT,
	.value.text = {
	.start = bcd->input.begin,
	.count = getInputCount(bcd)
	}
	},

	{ .name = NULL }
	};

	FILE *stream = bcd->table->data.external.standardInput;
	const ExternalRequestEntry *req = externalRequestTable;

	while (req->name) {
	if (fputs(req->name, stream) == EOF) goto outputError;
	if (fputc('=', stream) == EOF) goto outputError;

	switch (req->type) {
	case REQ_TEXT: {
	const wchar_t *character = req->value.text.start;
	const wchar_t *end = character + req->value.text.count;

	while (character < end) {
	Utf8Buffer utf8;
	size_t utfs = convertWcharToUtf8(*character++, utf8);

	if (!utfs) return 0;
	if (fputs(utf8, stream) == EOF) goto outputError;
	}

	break;
	}

	case REQ_NUMBER:
	if (fprintf(stream, "%u", req->value.number) == EOF) goto outputError;
	break;

	default:
	logMessage(LOG_WARNING, "unimplemented external contraction request property type: %s: %u (%s)", bcd->table->data.external.command, req->type, req->name);
	return 0;
	}

	if (fputc('\n', stream) == EOF) goto outputError;
	req += 1;
	}

	if (fflush(stream) == EOF) goto outputError;
	return 1;

	outputError:
	logMessage(LOG_WARNING, "external contraction output error: %s: %s", bcd->table->data.external.command, strerror(errno));
	return 0;
	}

	static const unsigned char brfTable[0X40] = {
	/* 0X20 */ 0,
	/* 0X21 ! */ BRL_DOT_2 \| BRL_DOT_3 \| BRL_DOT_4 \| BRL_DOT_6,
	/* 0X22 " */ BRL_DOT_5,
	/* 0X23 # */ BRL_DOT_3 \| BRL_DOT_4 \| BRL_DOT_5 \| BRL_DOT_6,
	/* 0X24 $ */ BRL_DOT_1 \| BRL_DOT_2 \| BRL_DOT_4 \| BRL_DOT_6,
	/* 0X25 % */ BRL_DOT_1 \| BRL_DOT_4 \| BRL_DOT_6,
	/* 0X26 & */ BRL_DOT_1 \| BRL_DOT_2 \| BRL_DOT_3 \| BRL_DOT_4 \| BRL_DOT_6,
	/* 0X27 ' */ BRL_DOT_3,
	/* 0X28 ( */ BRL_DOT_1 \| BRL_DOT_2 \| BRL_DOT_3 \| BRL_DOT_5 \| BRL_DOT_6,
	/* 0X29 ) */ BRL_DOT_2 \| BRL_DOT_3 \| BRL_DOT_4 \| BRL_DOT_5 \| BRL_DOT_6,
	/* 0X2A * */ BRL_DOT_1 \| BRL_DOT_6,
	/* 0X2B + */ BRL_DOT_3 \| BRL_DOT_4 \| BRL_DOT_6,
	/* 0X2C , */ BRL_DOT_6,
	/* 0X2D - */ BRL_DOT_3 \| BRL_DOT_6,
	/* 0X2E . */ BRL_DOT_4 \| BRL_DOT_6,
	/* 0X2F / */ BRL_DOT_3 \| BRL_DOT_4,
	/* 0X30 0 */ BRL_DOT_3 \| BRL_DOT_5 \| BRL_DOT_6,
	/* 0X31 1 */ BRL_DOT_2,
	/* 0X32 2 */ BRL_DOT_2 \| BRL_DOT_3,
	/* 0X33 3 */ BRL_DOT_2 \| BRL_DOT_5,
	/* 0X34 4 */ BRL_DOT_2 \| BRL_DOT_5 \| BRL_DOT_6,
	/* 0X35 5 */ BRL_DOT_2 \| BRL_DOT_6,
	/* 0X36 6 */ BRL_DOT_2 \| BRL_DOT_3 \| BRL_DOT_5,
	/* 0X37 7 */ BRL_DOT_2 \| BRL_DOT_3 \| BRL_DOT_5 \| BRL_DOT_6,
	/* 0X38 8 */ BRL_DOT_2 \| BRL_DOT_3 \| BRL_DOT_6,
	/* 0X39 9 */ BRL_DOT_3 \| BRL_DOT_5,
	/* 0X3A : */ BRL_DOT_1 \| BRL_DOT_5 \| BRL_DOT_6,
	/* 0X3B ; */ BRL_DOT_5 \| BRL_DOT_6,
	/* 0X3C < */ BRL_DOT_1 \| BRL_DOT_2 \| BRL_DOT_6,
	/* 0X3D = */ BRL_DOT_1 \| BRL_DOT_2 \| BRL_DOT_3 \| BRL_DOT_4 \| BRL_DOT_5 \| BRL_DOT_6,
	/* 0X3E > */ BRL_DOT_3 \| BRL_DOT_4 \| BRL_DOT_5,
	/* 0X3F ? */ BRL_DOT_1 \| BRL_DOT_4 \| BRL_DOT_5 \| BRL_DOT_6,
	/* 0X40 @ */ BRL_DOT_4,
	/* 0X41 A */ BRL_DOT_1,
	/* 0X42 B */ BRL_DOT_1 \| BRL_DOT_2,
	/* 0X43 C */ BRL_DOT_1 \| BRL_DOT_4,
	/* 0X44 D */ BRL_DOT_1 \| BRL_DOT_4 \| BRL_DOT_5,
	/* 0X45 E */ BRL_DOT_1 \| BRL_DOT_5,
	/* 0X46 F */ BRL_DOT_1 \| BRL_DOT_2 \| BRL_DOT_4,
	/* 0X47 G */ BRL_DOT_1 \| BRL_DOT_2 \| BRL_DOT_4 \| BRL_DOT_5,
	/* 0X48 H */ BRL_DOT_1 \| BRL_DOT_2 \| BRL_DOT_5,
	/* 0X49 I */ BRL_DOT_2 \| BRL_DOT_4,
	/* 0X4A J */ BRL_DOT_2 \| BRL_DOT_4 \| BRL_DOT_5,
	/* 0X4B K */ BRL_DOT_1 \| BRL_DOT_3,
	/* 0X4C L */ BRL_DOT_1 \| BRL_DOT_2 \| BRL_DOT_3,
	/* 0X4D M */ BRL_DOT_1 \| BRL_DOT_3 \| BRL_DOT_4,
	/* 0X4E N */ BRL_DOT_1 \| BRL_DOT_3 \| BRL_DOT_4 \| BRL_DOT_5,
	/* 0X4F O */ BRL_DOT_1 \| BRL_DOT_3 \| BRL_DOT_5,
	/* 0X50 P */ BRL_DOT_1 \| BRL_DOT_2 \| BRL_DOT_3 \| BRL_DOT_4,
	/* 0X51 Q */ BRL_DOT_1 \| BRL_DOT_2 \| BRL_DOT_3 \| BRL_DOT_4 \| BRL_DOT_5,
	/* 0X52 R */ BRL_DOT_1 \| BRL_DOT_2 \| BRL_DOT_3 \| BRL_DOT_5,
	/* 0X53 S */ BRL_DOT_2 \| BRL_DOT_3 \| BRL_DOT_4,
	/* 0X54 T */ BRL_DOT_2 \| BRL_DOT_3 \| BRL_DOT_4 \| BRL_DOT_5,
	/* 0X55 U */ BRL_DOT_1 \| BRL_DOT_3 \| BRL_DOT_6,
	/* 0X56 V */ BRL_DOT_1 \| BRL_DOT_2 \| BRL_DOT_3 \| BRL_DOT_6,
	/* 0X57 W */ BRL_DOT_2 \| BRL_DOT_4 \| BRL_DOT_5 \| BRL_DOT_6,
	/* 0X58 X */ BRL_DOT_1 \| BRL_DOT_3 \| BRL_DOT_4 \| BRL_DOT_6,
	/* 0X59 Y */ BRL_DOT_1 \| BRL_DOT_3 \| BRL_DOT_4 \| BRL_DOT_5 \| BRL_DOT_6,
	/* 0X5A Z */ BRL_DOT_1 \| BRL_DOT_3 \| BRL_DOT_5 \| BRL_DOT_6,
	/* 0X5B [ */ BRL_DOT_2 \| BRL_DOT_4 \| BRL_DOT_6,
	/* 0X5C \ */ BRL_DOT_1 \| BRL_DOT_2 \| BRL_DOT_5 \| BRL_DOT_6,
	/* 0X5D ] */ BRL_DOT_1 \| BRL_DOT_2 \| BRL_DOT_4 \| BRL_DOT_5 \| BRL_DOT_6,
	/* 0X5E ^ */ BRL_DOT_4 \| BRL_DOT_5,
	/* 0X5F _ */ BRL_DOT_4 \| BRL_DOT_5 \| BRL_DOT_6
	};

	static int
	handleExternalResponse_brf (BrailleContractionData bcd, const char value) {
	int useDot7 = prefs.capitalizationMode == CTB_CAP_DOT7;

	while (*value && (bcd->output.current < bcd->output.end)) {
	unsigned char brf = *value++ & 0XFF;
	unsigned char dots = 0;
	unsigned char superimpose = 0;

	if ((brf >= 0X60) && (brf <= 0X7F)) {
	brf -= 0X20;
	} else if ((brf >= 0X41) && (brf <= 0X5A)) {
	if (useDot7) superimpose \|= BRL_DOT_7;
	}

	if ((brf >= 0X20) && (brf <= 0X5F)) dots = brfTable[brf - 0X20] \| superimpose;
	*bcd->output.current++ = dots;
	}

	return 1;
	}

	static int
	handleExternalResponse_consumedLength (BrailleContractionData bcd, const char value) {
	int length;

	if (!isInteger(&length, value)) return 0;
	if (length < 1) return 0;
	if (length > getInputCount(bcd)) return 0;

	bcd->input.current = bcd->input.begin + length;
	return 1;
	}

	static int
	handleExternalResponse_outputOffsets (BrailleContractionData bcd, const char value) {
	if (bcd->input.offsets) {
	int previous = CTB_NO_OFFSET;
	unsigned int count = getInputCount(bcd);
	unsigned int index = 0;

	while (*value && (index < count)) {
	int offset;

	{
	char *delimiter = strchr(value, ',');

	if (delimiter) {
	int ok;

	{
	char oldDelimiter = *delimiter;
	*delimiter = 0;
	ok = isInteger(&offset, value);
	*delimiter = oldDelimiter;
	}

	if (!ok) return 0;
	value = delimiter + 1;
	} else if (isInteger(&offset, value)) {
	value += strlen(value);
	} else {
	return 0;
	}
	}

	if (offset < ((index == 0)? 0: previous)) return 0;
	if (offset >= getOutputCount(bcd)) return 0;

	bcd->input.offsets[index++] = (offset == previous)? CTB_NO_OFFSET: offset;
	previous = offset;
	}
	}

	return 1;
	}

	typedef struct {
	const char *name;
	int (handler) (BrailleContractionData bcd, const char *value);
	unsigned stop:1;
	} ExternalResponseEntry;

	static const ExternalResponseEntry externalResponseTable[] = {
	{ .name = "brf",
	.stop = 1,
	.handler = handleExternalResponse_brf
	},

	{ .name = "consumed-length",
	.handler = handleExternalResponse_consumedLength
	},

	{ .name = "output-offsets",
	.handler = handleExternalResponse_outputOffsets
	},

	{ .name = NULL }
	};

	static int
	getExternalResponses (BrailleContractionData *bcd) {
	FILE *stream = bcd->table->data.external.standardOutput;

	while (readLine(stream, &bcd->table->data.external.input.buffer, &bcd->table->data.external.input.size, NULL)) {
	int ok = 0;
	int stop = 0;
	char *delimiter = strchr(bcd->table->data.external.input.buffer, '=');

	if (delimiter) {
	const char *value = delimiter + 1;
	const ExternalResponseEntry *rsp = externalResponseTable;

	char oldDelimiter = *delimiter;
	*delimiter = 0;

	while (rsp->name) {
	if (strcmp(bcd->table->data.external.input.buffer, rsp->name) == 0) {
	if (rsp->handler(bcd, value)) ok = 1;
	if (rsp->stop) stop = 1;
	break;
	}

	rsp += 1;
	}

	*delimiter = oldDelimiter;
	}

	if (!ok) logMessage(LOG_WARNING, "unexpected external contraction response: %s: %s", bcd->table->data.external.command, bcd->table->data.external.input.buffer);
	if (stop) return 1;
	}

	logMessage(LOG_WARNING, "incomplete external contraction response: %s", bcd->table->data.external.command);
	return 0;
	}

	static int
	contractText_external (BrailleContractionData *bcd) {
	setOffset(bcd);
	while (++bcd->input.current < bcd->input.end) clearOffset(bcd);

	if (startContractionCommand(bcd->table)) {
	if (putExternalRequests(bcd)) {
	if (getExternalResponses(bcd)) {
	return 1;
	}
	}
	}

	stopContractionCommand(bcd->table);
	return 0;
	}

	static void
	finishCharacterEntry_external (BrailleContractionData bcd, CharacterEntry entry) {
	}

	static const ContractionTableTranslationMethods externalTranslationMethods = {
	.contractText = contractText_external,
	.finishCharacterEntry = finishCharacterEntry_external
	};

	const ContractionTableTranslationMethods *
	getContractionTableTranslationMethods_external (void) {
	return &externalTranslationMethods;
	}