prql-lib with Zig

[vanillajonathan]

I never wrote any Zig code before but today I made an attempt to create a "minimal Zig" example that uses prql-lib.

main.zig

const std = @import("std");
const prql = @cImport({
    @cInclude("libprql_lib.h");
});

pub fn main() void {
    // Setup PRQL compiler options
    var target = "sql.mssql".*;
    const options = prql.Options{
        .format = false,
        .signature_comment = false,
        .target = &target,
    };

    // Compile the PRQL query
    const prql_query = "from albums | select {album_id, title} | take 3";
    const result = prql.compile(prql_query, &options);
    defer prql.result_destroy(result);

    std.debug.print("Compiled with {d} errors\n", .{result.messages_len});
    std.debug.print("Output:\n\n{s}\n", .{result.output});
}

Then I try to compile with:

zig run main.zig -lc -isystem <path/to/libprql_lib.h>

Unfortunately I haven't gotten it working.

Maybe working directly against the C library isn't so user-friendly, and maybe some wrapper functions could be used?

Maybe something along the lines of the code below.

prql.zig

const prql = @cImport({
    @cInclude("libprql_lib.h");
});

/// Compile a PRQL string into a SQL string.
pub fn compile(prql_query: []const u8, options: *Options) CompileResult {
    // Not implemented

    const prql_options = prql.Options{
        .format = options.format,
        .signature_comment = options.signature_comment,
        .target = options.target,
    };

    return prql.compile(&prql_query, &prql_options);
}

/// Result of compilation.
pub const CompileResult = struct {
    output: []const u8,
    messages: []Message,
    messages_len: usize,

    /// Compile result message.
    pub const Message = struct {
        kind: MessageKind,
        reason: []const u8,
        span: Span,
        location: SourceLocation,

        /// Compile message kind. Currently only Error is implemented.
        pub const MessageKind = enum {
            "error",
            warning,
            lint,
        };

        /// Location within a source file.
        pub const SourceLocation = struct {
            start_line: usize,
            start_col: usize,
            end_line: usize,
            end_col: usize,
        };

        /// Identifier of a location in source.
        /// Contains offsets in terms of chars.
        pub const Span = struct {
            start: usize,
            end: usize,
        };
    };
};

/// Compilation options.
pub const Options = struct {
    format: bool,
    signature_comment: bool,
    target: []const u8,
};

[max-sixty]

That's cool re zig! I've heard lots about it.

(unfortunately I've never tried it, so won't be much help; though prql-lib does seem to work with other bindings, so I'm guessing the issue is more on the zig side?)

[max-sixty]

Done! #3372