Re: RFR: Improve formatting of generated source code [v2]

15 Dec 2023


      ...
As a main rule-of-thumb: we should generate a blank line before a multi-line declaration, or before a block of single line declarations (e.g. fields, or methods collapsed into a single line).
In most cases, we can just add a blank line to the start of the String template we use. In some cases that emit single-line declarations, we have a manual call to `appendBlankLine` before emitting multiple single line decls. For declarations with comments we also add the blank line manually, as there shouldn't be a blank line between the comment and declaration.
- I've also added the default constructor to every class we generate, and moved it before the layout decl in struct classes (makes a little bit more sense I think).
- fixed the indentation and excess trailing whitespace after the class `}` of a class.
- Fixed the way in which we add indentation to text blocks, so that we don't add trailing white space to empty lines.
<details>
<summary>Sample output (click to unfold)</summary>
For instance for this header:
struct Foo {
    int x;
    struct Bar {
        int y;
    } bar;
};
typedef struct Foo (*CB)(void);
Foo.java:
// Generated by jextract
import java.lang.invoke.MethodHandle;
import java.lang.invoke.MethodHandles;
import java.lang.invoke.VarHandle;
import java.nio.ByteOrder;
import java.lang.foreign.*;
import static java.lang.foreign.ValueLayout.*;
/**
 * {@snippet lang=c :
 * struct Foo {
 *     int x;
 *     struct Bar bar;
 * };
 * }
 */
public class Foo {
Foo() {
        // Suppresses public default constructor, ensuring non-instantiability,
        // but allows generated subclasses in same package.
    }
private static final GroupLayout $LAYOUT = MemoryLayout.structLayout(
        struct_with_fptr_h.C_INT.withName("x"),
        Foo.Bar.$LAYOUT().withName("bar")
    ).withName("Foo");
public static final GroupLayout $LAYOUT() {
        return $LAYOUT;
    }
private static final long x$OFFSET = 0;
/**
     * Getter for field:
     * {@snippet lang=c :
     * int x;
     * }
     */
    public static int x$get(MemorySegment seg) {
        return seg.get(struct_with_fptr_h.C_INT, x$OFFSET);
    }
public static int x$get(MemorySegment seg, long index) {
        return seg.get(struct_with_fptr_h.C_INT, x$OFFSET + (index * sizeof()));
    }
/**
     * Setter for field:
     * {@snippet lang=c :
     * int x;
     * }
     */
    public static void x$set(MemorySegment seg, int x) {
        seg.set(struct_with_fptr_...
Jorn Vernee has updated the pull request incrementally with one additional commit since the last revision:

  review comments

-------------

Changes:
  - all: https://git.openjdk.org/jextract/pull/166/files
  - new: https://git.openjdk.org/jextract/pull/166/files/2ff1d53a..14112489

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jextract&pr=166&range=01
 - incr: https://webrevs.openjdk.org/?repo=jextract&pr=166&range=00-01

  Stats: 14 lines in 1 file changed: 3 ins; 5 del; 6 mod
  Patch: https://git.openjdk.org/jextract/pull/166.diff
  Fetch: git fetch https://git.openjdk.org/jextract.git pull/166/head:pull/166

PR: https://git.openjdk.org/jextract/pull/166