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1 Current terminal widget: |
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2 |
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3 * Run Octave in a separate thread. On unixy, interact through pty. |
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4 On Windows systems, use hidden console and mirror contents in Qt |
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5 widget. |
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6 |
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7 Octave interpreter sees input directly, same as for normal |
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8 terminal application. Good, because no change in the way Octave |
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9 accepts and parses input. Bad because GUI is not in control of |
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10 input and must arrange to communicate across threads. |
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11 |
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12 Terminal window can (in theory) be used to run other applications |
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13 started from the system command (for example). This feature works |
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14 well enough for us to use less running as a separate process to |
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15 handle paging output, but it doesn't work for all applications. |
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16 For example, I am not able to run editors like Emacs or vi in the |
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17 GUI terminal window. |
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18 |
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19 To make less work as the pager on Unixy systems, the Octave must |
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20 fork, call setsid in the child to detach from the controlling |
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21 terminal, and then exec the GUI. |
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22 |
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23 GUI must deal with threads when communicating with the |
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24 interpreter. |
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25 |
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26 Proposal: |
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27 |
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28 * GUI terminal widget is in control of input. |
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29 |
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30 Use callback interface for readline to handle command line |
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31 editing. |
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32 |
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33 Use push parser to parse lines as they become available. Push |
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34 parser will return status of parse, either complete or needing |
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35 more input. |
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36 |
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37 Uses the following readline callbacks to manage input and update |
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38 the display. We may need more in the future to handle other |
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39 features. |
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40 |
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41 rl_getc_function |
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42 rl_redisplay_function |
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43 rl_completion_display_matches_hook |
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44 |
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45 rl_prep_term_function (do nothing) |
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46 rl_deprep_term_function (do nothing) |
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47 |
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48 Call rl_callback_handler_install to setup readlines |
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49 callback mode. This sets the initial prompt and provides a pointer |
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50 to a function that readline should call when a complete line of |
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51 input is available. |
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52 |
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53 Call rl_callback_read_char when a character is available for |
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54 readline to handle. We currently store the character to read in a |
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55 global value, then rl_get_function returns that character to |
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56 readline. |
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57 |
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58 Call rl_callback_handler_remove when shutting down. |
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59 |
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60 To avoid global variables, it would be helpful if we could use |
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61 lambda functions/functors as callbacks instead of plain C function |
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62 pointers. |
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63 |
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64 Questions: |
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65 |
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66 * With this arrangement, would the interpreter have to run in a |
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67 separtae thread? |
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68 |
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69 * Example parser currently computes results |
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70 immediately. How do we deal with parsing multiple expressions and |
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71 statements with this method? |
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72 |
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73 * Do we need text position markers to keep track of the prompt position |
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74 (beginning of current line) when inserting or clearing text? |
