strbuilder

4 files changed, 300 insertions, 0 deletions

diff --git a/scripts/strbuilder/build.zig b/scripts/strbuilder/build.zig
new file mode 100644
index 0000000..c8a0c23
--- /dev/null
+++ b/scripts/strbuilder/build.zig
@@ -0,0 +1,91 @@
+const std = @import("std");
+
+// Although this function looks imperative, note that its job is to
+// declaratively construct a build graph that will be executed by an external
+// runner.
+pub fn build(b: *std.Build) void {
+    // Standard target options allows the person running `zig build` to choose
+    // what target to build for. Here we do not override the defaults, which
+    // means any target is allowed, and the default is native. Other options
+    // for restricting supported target set are available.
+    const target = b.standardTargetOptions(.{});
+
+    // Standard optimization options allow the person running `zig build` to select
+    // between Debug, ReleaseSafe, ReleaseFast, and ReleaseSmall. Here we do not
+    // set a preferred release mode, allowing the user to decide how to optimize.
+    const optimize = b.standardOptimizeOption(.{});
+
+    const lib = b.addStaticLibrary(.{
+        .name = "strbuilder",
+        // In this case the main source file is merely a path, however, in more
+        // complicated build scripts, this could be a generated file.
+        .root_source_file = b.path("src/root.zig"),
+        .target = target,
+        .optimize = optimize,
+    });
+
+    // This declares intent for the library to be installed into the standard
+    // location when the user invokes the "install" step (the default step when
+    // running `zig build`).
+    b.installArtifact(lib);
+
+    const exe = b.addExecutable(.{
+        .name = "strbuilder",
+        .root_source_file = b.path("src/main.zig"),
+        .target = target,
+        .optimize = optimize,
+    });
+
+    // This declares intent for the executable to be installed into the
+    // standard location when the user invokes the "install" step (the default
+    // step when running `zig build`).
+    b.installArtifact(exe);
+
+    // This *creates* a Run step in the build graph, to be executed when another
+    // step is evaluated that depends on it. The next line below will establish
+    // such a dependency.
+    const run_cmd = b.addRunArtifact(exe);
+
+    // By making the run step depend on the install step, it will be run from the
+    // installation directory rather than directly from within the cache directory.
+    // This is not necessary, however, if the application depends on other installed
+    // files, this ensures they will be present and in the expected location.
+    run_cmd.step.dependOn(b.getInstallStep());
+
+    // This allows the user to pass arguments to the application in the build
+    // command itself, like this: `zig build run -- arg1 arg2 etc`
+    if (b.args) |args| {
+        run_cmd.addArgs(args);
+    }
+
+    // This creates a build step. It will be visible in the `zig build --help` menu,
+    // and can be selected like this: `zig build run`
+    // This will evaluate the `run` step rather than the default, which is "install".
+    const run_step = b.step("run", "Run the app");
+    run_step.dependOn(&run_cmd.step);
+
+    // Creates a step for unit testing. This only builds the test executable
+    // but does not run it.
+    const lib_unit_tests = b.addTest(.{
+        .root_source_file = b.path("src/root.zig"),
+        .target = target,
+        .optimize = optimize,
+    });
+
+    const run_lib_unit_tests = b.addRunArtifact(lib_unit_tests);
+
+    const exe_unit_tests = b.addTest(.{
+        .root_source_file = b.path("src/main.zig"),
+        .target = target,
+        .optimize = optimize,
+    });
+
+    const run_exe_unit_tests = b.addRunArtifact(exe_unit_tests);
+
+    // Similar to creating the run step earlier, this exposes a `test` step to
+    // the `zig build --help` menu, providing a way for the user to request
+    // running the unit tests.
+    const test_step = b.step("test", "Run unit tests");
+    test_step.dependOn(&run_lib_unit_tests.step);
+    test_step.dependOn(&run_exe_unit_tests.step);
+}
diff --git a/scripts/strbuilder/build.zig.zon b/scripts/strbuilder/build.zig.zon
new file mode 100644
index 0000000..3ce0186
--- /dev/null
+++ b/scripts/strbuilder/build.zig.zon
@@ -0,0 +1,72 @@
+.{
+    // This is the default name used by packages depending on this one. For
+    // example, when a user runs `zig fetch --save <url>`, this field is used
+    // as the key in the `dependencies` table. Although the user can choose a
+    // different name, most users will stick with this provided value.
+    //
+    // It is redundant to include "zig" in this name because it is already
+    // within the Zig package namespace.
+    .name = "strbuilder",
+
+    // This is a [Semantic Version](https://semver.org/).
+    // In a future version of Zig it will be used for package deduplication.
+    .version = "0.0.0",
+
+    // This field is optional.
+    // This is currently advisory only; Zig does not yet do anything
+    // with this value.
+    //.minimum_zig_version = "0.11.0",
+
+    // This field is optional.
+    // Each dependency must either provide a `url` and `hash`, or a `path`.
+    // `zig build --fetch` can be used to fetch all dependencies of a package, recursively.
+    // Once all dependencies are fetched, `zig build` no longer requires
+    // internet connectivity.
+    .dependencies = .{
+        // See `zig fetch --save <url>` for a command-line interface for adding dependencies.
+        //.example = .{
+        //    // When updating this field to a new URL, be sure to delete the corresponding
+        //    // `hash`, otherwise you are communicating that you expect to find the old hash at
+        //    // the new URL.
+        //    .url = "https://example.com/foo.tar.gz",
+        //
+        //    // This is computed from the file contents of the directory of files that is
+        //    // obtained after fetching `url` and applying the inclusion rules given by
+        //    // `paths`.
+        //    //
+        //    // This field is the source of truth; packages do not come from a `url`; they
+        //    // come from a `hash`. `url` is just one of many possible mirrors for how to
+        //    // obtain a package matching this `hash`.
+        //    //
+        //    // Uses the [multihash](https://multiformats.io/multihash/) format.
+        //    .hash = "...",
+        //
+        //    // When this is provided, the package is found in a directory relative to the
+        //    // build root. In this case the package's hash is irrelevant and therefore not
+        //    // computed. This field and `url` are mutually exclusive.
+        //    .path = "foo",
+
+        //    // When this is set to `true`, a package is declared to be lazily
+        //    // fetched. This makes the dependency only get fetched if it is
+        //    // actually used.
+        //    .lazy = false,
+        //},
+    },
+
+    // Specifies the set of files and directories that are included in this package.
+    // Only files and directories listed here are included in the `hash` that
+    // is computed for this package. Only files listed here will remain on disk
+    // when using the zig package manager. As a rule of thumb, one should list
+    // files required for compilation plus any license(s).
+    // Paths are relative to the build root. Use the empty string (`""`) to refer to
+    // the build root itself.
+    // A directory listed here means that all files within, recursively, are included.
+    .paths = .{
+        "build.zig",
+        "build.zig.zon",
+        "src",
+        // For example...
+        //"LICENSE",
+        //"README.md",
+    },
+}
diff --git a/scripts/strbuilder/src/main.zig b/scripts/strbuilder/src/main.zig
new file mode 100644
index 0000000..c8a3f67
--- /dev/null
+++ b/scripts/strbuilder/src/main.zig
@@ -0,0 +1,24 @@
+const std = @import("std");
+
+pub fn main() !void {
+    // Prints to stderr (it's a shortcut based on `std.io.getStdErr()`)
+    std.debug.print("All your {s} are belong to us.\n", .{"codebase"});
+
+    // stdout is for the actual output of your application, for example if you
+    // are implementing gzip, then only the compressed bytes should be sent to
+    // stdout, not any debugging messages.
+    const stdout_file = std.io.getStdOut().writer();
+    var bw = std.io.bufferedWriter(stdout_file);
+    const stdout = bw.writer();
+
+    try stdout.print("Run `zig build test` to run the tests.\n", .{});
+
+    try bw.flush(); // don't forget to flush!
+}
+
+test "simple test" {
+    var list = std.ArrayList(i32).init(std.testing.allocator);
+    defer list.deinit(); // try commenting this out and see if zig detects the memory leak!
+    try list.append(42);
+    try std.testing.expectEqual(@as(i32, 42), list.pop());
+}
diff --git a/scripts/strbuilder/src/root.zig b/scripts/strbuilder/src/root.zig
new file mode 100644
index 0000000..bcaf445
--- /dev/null
+++ b/scripts/strbuilder/src/root.zig
@@ -0,0 +1,113 @@
+const std = @import("std");
+const testing = std.testing;
+const Allocator = std.heap.Allocator;
+const ArrayList = std.ArrayList;
+
+// Considerations
+// When doing replaces, each replace may need to factor in previous replaces, deletes, etc.
+// E.g. the text "Hi (Deletedah) ahThere" will be -2 bytes with replace("ah", "") after the
+// deletion has occurred, but if naively written, then -4 bytes will be calculated for.
+
+const OpTag = enum {
+    append,
+    prepend,
+    insert,
+    replace_all,
+};
+
+const Op = union(OpTag) {
+    append: struct { s: []const u8 },
+    prepend: struct { s: []const u8 },
+    insert: struct { pos: usize, s: []const u8 },
+    replace_all: struct { old: []const u8, new: []const u8, additional_bytes_to_allocate: isize },
+};
+
+// TODO
+export const StrBuilder = struct {
+    allocator: Allocator,
+    ops: ArrayList(Op),
+    base: []const u8,
+
+    pub fn new(allocator: Allocator, base: []const u8) StrBuilder {
+        var ret = StrBuilder{};
+        ret.allocator = allocator;
+        ret.ops = ArrayList(Op).init(allocator);
+        ret.base = base;
+
+        return ret;
+    }
+
+    pub fn build(self: StrBuilder) []const u8 {
+        // TODO
+    }
+
+    pub fn deinit(self: StrBuilder) void {
+        self.ops.deinit();
+    }
+
+    pub fn append(self: StrBuilder, s: []const u8) void {
+        self.ops.append(Op{ .append = .{ .s = s } });
+    }
+    pub fn prepend(self: StrBuilder, s: []const u8) void {
+        self.ops.append(Op{ .prepend = .{ .s = s } });
+    }
+    pub fn insert(self: StrBuilder, pos: usize, s: []const u8) void {
+        self.ops.append(Op{ .insert = .{ .pos = pos, .s = s } });
+    }
+    pub fn replaceAll(self: StrBuilder, old_str: []const u8, new_str: []const u8) void {
+        // TODO: find count of `old` and store the additional allocatable size in the enum(union).
+        // Signed (isize) so as to allow the case when old.len > new.len.
+        const additional_bytes_req: isize = std.mem.count(u8, self.base, self.old) * (new.len - old.len);
+        self.ops.append(Op{ .replace_all = .{ .old = old_str, .new = new_str, .additional_bytes_to_allocate = additional_bytes_req } });
+    }
+    /// If the line matches the given predicate, delete the line.
+    pub fn deleteLineIf(self: StrBuilder, pred: fn (line: []const u8) bool) void {
+        // TODO
+    }
+
+    /// Replaces a prefix in all lines if the line begins with said prefix.
+    pub fn replacePrefixLinewise(self: StrBuilder, old_prefix: []const u8, new_prefix: []const u8) void {
+        // TODO
+    }
+
+    // Used for replacing text of the form: P*I*S where P is a common prefix, I
+    // an infix, and S a suffix. Any text can occur in * (though consider opts).
+    // Useful, e.g. to turn @@[text][href] into <a href="href">text</a>.
+    pub const ReplaceBipartOpts = struct {
+        allowNewline: bool,
+    };
+    pub fn replaceBipart(
+        self: StrBuilder,
+        p: []const u8,
+        i: []const u8,
+        s: []const u8,
+        new_p: []const u8,
+        new_i: []const u8,
+        new_s: []const u8,
+        opts: ReplaceBipartOpts,
+    ) void {
+        // TODO
+    }
+
+    pub fn calculateSizeToAllocate(self: StrBuilder) usize {
+        var diff: isize = 0;
+        for (self.ops.items) |op| {
+            switch (op) {
+                OpTag.append, OpTag.prepend => |s| {
+                    diff += s.len;
+                },
+                OpTag.insert => |c| {
+                    diff += c.s.len;
+                },
+                OpTag.replace_all => |c| {
+                    diff += c.additional_bytes_to_allocate;
+                },
+            }
+        }
+        return self.base.len + diff;
+    }
+};
+
+test "basic add functionality" {
+    try testing.expect(add(3, 7) == 10);
+}