System and method for horizontal alignment of tokens in a structural representation program editor

• US 5,857,212 A
• Filed: 09/12/1996
• Issued: 01/05/1999
• Est. Priority Date: 07/06/1995
• Status: Expired due to Fees

• Current Assignee: Sun Microsystems Incorporated (Oracle Corporation)
• Original Assignee: Sun Microsystems Incorporated (Oracle Corporation)
• Inventors: Van De Vanter, Michael L.
• Primary Examiner(s): Burwell, Joseph R.
• Application Number:
  US08/713,062
• Time in Patent Office: 845 Days
• Field of Search: 707/530, 707/531, 707/527, 707/519, 395/701
• US Class Current: 715/234
• CPC Class Codes: G06F 8/33 Intelligent editors

Abstract

An editor for structurally represented computer programs transforms user-entered text on-the-fly into a stream of tokens that constitute words of the program under edit. Each token is classified as one of group of extended lexemes, and based upon token stream information the editor prettyprint displays the program as the user types. Prettyprinting involves typesetting each token in a visually distinct manner and displaying a varying amount of visual inter-token whitespace between the tokens, based upon token lexical type. The program may be user-edited from the prettyprinted display as though the program were internally represented as text. Cursor position and display appearance depend on the lexical types of tokens adjacent the cursor. To improve aesthetics of the prettyprinted display, a user may insert one or more alignment markers into lines of associated text. The presence of such marker(s) forces horizontal alignment between associated text lines containing such markers. The presence, number, and occurrence of such markers in associated lines of text is noted, and the pixel distance from a boundary edge to the first occurring marker in each line is calculated. The maximum such distance determines relative position of the first alignment marker. Pixel units are added to the whitespace gap preceding the first marker in the other associated lines to force such markers into alignment with the marker whose position represented the maximum distance. This process is then repeated for second alignment markers in each line, third alignment markers, and so on.

Claims

1. In a computer program editor configured to edit a computer program represented as a stream of tokens from a text flow representation display of said program, a method for forcing horizontal alignment between token positions in associated lines of edit text, the method comprising the following steps:

(a) displaying each line of said computer program as it is entered by a user, wherein a displayed line represents a sequence of tokens and visual whitespace separating adjacent tokens;

(b) defining at least a first cursor-positionable alignment marker at a first insertion point in said stream corresponding to a user-selected first inter-token position in a first said displayed line, and defining at least a second cursor-positional alignment marker at a second insertion point in said stream corresponding to a user-selected second inter-token position in a second said display line of said computer program, said first display line and said second display line being associated with one another, each said alignment marker providing user interactability with a said displayed line;

(c) prettyprint displaying said first displayed line and said second displayed line such that said first inter-token position and said second inter-token position are forced into horizontal alignment with each other;

wherein a token adjacent said first inter-token position and a token adjacent said second inter-token position are themselves displayed in relative horizontal alignment; and

(d) maintaining boundaries between each said token and updating each said insertion position while said user edits a said line of said computer program as though said user were editing a said line of said computer program with a text editor.

2. The method of claim 1, wherein at step (b) a user defines a position of a said alignment marker using an input device coupled to said editor, while viewing said display.

3. The method of claim 1, wherein at least one said alignment marker has at least one characteristic selected from the group consisting of (i) said alignment marker is always visible on said display, (ii) said alignment marker is visible on said display only in a reveal alignment marker mode, (iii) said alignment marker is less intensely visible on said display than is text, and (iv) said alignment marker is visible on said display in a color other than what is used to display text on said display.

4. The method of claim 1, wherein said lines are associated if (i) they are unseparated by a blank line, (ii) they are not immediately preceded by a line having a different indentation, (iii) they are not immediately followed by a line having a different indentation, or (iv) a combination of (i), (ii), and (iii).

5. The method of claim 1, wherein step (c) includes selectively modulating horizontal width of whitespace in a said inter-token position to force horizontal alignment of a said token bounded by said whitespace.

6. The method of claim 1, wherein step (c) includes the following steps:

(i) identifying each line in said computer program for which at least one alignment marker was defined by a user;

(ii) identifying each other line in said computer program associated with a said line identified at step (i);

(iii) establishing a positional occurrence order for each said alignment marker in each line identified in step (i) or (ii);

(iv) for each line identified in step (i) or (ii), determining a horizontal distance from a display edit boundary to a position of a token whose inter-token position includes a first occurring said alignment marker;

(v) identifying at step (iv) a maximum said horizontal distance that is associated with a said token whose inter-token position includes a said alignment marker; and

(vi) modulating whitespace associated with a remaining said token whose inter-token position includes a remaining said alignment marker, so as to horizontally relocate the remaining token such that it aligns horizontally with said token referred to in step (v).

7. The method of claim 6, wherein:

step (iv) further includes determining a horizontal distance from a display edit boundary to a position of a token whose inter-token position includes an Nth-occurring said alignment marker;

step (v) further includes identifying at step (iv) a maximum said horizontal distance that is associated with a said token whose inter-token position includes a said Nth-occurring alignment marker; and

step (vi) further includes modulating whitespace associated with an Nth-remaining said token whose inter-token position includes a remaining Nth-occurring said alignment marker, so as to horizontally relocate said Nth-remaining token such that it aligns horizontally with said Nth-occurring token referred to in step (v).

8. The method of claim 6, wherein:

at step (iv), said edit boundary is associated with a left edge of said display; and

at step (vi) said modulating includes incrementing said whitespace by a horizontal amount of space equal to a difference between the maximum horizontal distance identified at step (v) and a lesser said horizontal distance identified at step (iv).

9. A system permitting user-invoked horizontal alignment of token positions in associated text lines in a computer program editor that represents a computer program under edit as a stream of tokens and permits editing from a display of said program as though said program were represented as a text flow, the system comprising:

an input device configured to receive user-intended editing actions and to output an event stream of input events corresponding to said editing actions, said input events including at least a user defined first cursor-positionable alignment marker at a first insertion point in said stream corresponding to a user-selected first inter-token position in a first displayed line, and at least a user defined second cursor-positional alignment marker at a second insertion point in said stream corresponding to a user-selected second inter-token position in a second display line of said computer program, said first display line and said second display line being associated with one another and each said alignment marker providing user interactability with a said displayed line;

a typographical display processor configured to determine said cursor-defined position and to display each line of said computer program as it is entered and to display said first displayed line and said second displayed line such that said a token bounded by said first inter-token position and a token bounded by said second inter-token position are displayed in horizontal alignment if said first displayed line and said second displayed line are associated.

10. The system of claim 9, wherein said typographic display processor causes said display to visibly display each said alignment marker.

11. The system of claim 9, wherein said typographic display processor selectively modulates horizontal width of whitespace in a said inter-token position to force horizontal alignment of a said token bounded by said whitespace.

12. The system of claim 9, wherein said typographic display processor is configured to carry out the following steps:

(a) identifying each line in said computer program for which at least one alignment marker was defined by a user;

(b) identifying each other line in said computer program associated with a said line identified at step (a);

(c) establishing a positional occurrence order for each said alignment marker in each line identified in step (a) or (b);

(d) for each line identified in step (a) or (b), determining a horizontal distance from a display edit boundary to a position of a token whose inter-token position includes a first occurring said alignment marker;

(e) identifying at step (d) a maximum said horizontal distance that is associated with a said token whose inter-token position includes a said alignment marker; and

(f) modulating whitespace associated with a remaining said token whose inter-token position includes a remaining said alignment marker, so as to horizontally relocate the remaining token such that it aligns horizontally with said token referred to in step (e).

13. The system of claim 12, wherein said typographic display processor:

at step (d) further determines a horizontal distance from a display edit boundary to a position of a token whose inter-token position includes an Nth-occurring said alignment marker;

at step (e) further identifies at step (d) a maximum said horizontal distance that is associated with a said token whose inter-token position includes a said Nth-occurring alignment marker; and

at step (f) modulates whitespace associated with an Nth-remaining said token whose inter-token position includes a remaining Nth-occurring said alignment marker, so as to horizontally relocate said Nth-remaining token such that it aligns horizontally with said Nth-occurring token referred to in step (e).

14. The system of claim 9, wherein said first displayed line and said second displayed line are associated if (i) they are unseparated by a blank line, (ii) they are not immediately preceded by a line having a different indentation, (iii) they are not immediately followed by a line having a different indentation, or (iv) a combination of (i), (ii), and (iii).