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const std = @import("std");
const mem = std.mem;
const Allocator = mem.Allocator;
const StringIndexAdapter = std.hash_map.StringIndexAdapter;
const StringIndexContext = std.hash_map.StringIndexContext;
pub fn StringTable(comptime log_scope: @Type(.EnumLiteral)) type {
return struct {
const Self = @This();
const log = std.log.scoped(log_scope);
buffer: std.ArrayListUnmanaged(u8) = .{},
table: std.HashMapUnmanaged(u32, bool, StringIndexContext, std.hash_map.default_max_load_percentage) = .{},
pub fn deinit(self: *Self, gpa: Allocator) void {
self.buffer.deinit(gpa);
self.table.deinit(gpa);
}
pub fn toOwnedSlice(self: *Self, gpa: Allocator) []const u8 {
const result = self.buffer.toOwnedSlice(gpa);
self.table.clearRetainingCapacity();
return result;
}
pub const PrunedResult = struct {
buffer: []const u8,
idx_map: std.AutoHashMap(u32, u32),
};
pub fn toPrunedResult(self: *Self, gpa: Allocator) !PrunedResult {
var buffer = std.ArrayList(u8).init(gpa);
defer buffer.deinit();
try buffer.ensureTotalCapacity(self.buffer.items.len);
buffer.appendAssumeCapacity(0);
var idx_map = std.AutoHashMap(u32, u32).init(gpa);
errdefer idx_map.deinit();
try idx_map.ensureTotalCapacity(self.table.count());
var it = self.table.iterator();
while (it.next()) |entry| {
const off = entry.key_ptr.*;
const save = entry.value_ptr.*;
if (!save) continue;
const new_off = @as(u32, @intCast(buffer.items.len));
buffer.appendSliceAssumeCapacity(self.getAssumeExists(off));
idx_map.putAssumeCapacityNoClobber(off, new_off);
}
self.buffer.clearRetainingCapacity();
self.table.clearRetainingCapacity();
return PrunedResult{
.buffer = buffer.toOwnedSlice(),
.idx_map = idx_map,
};
}
pub fn insert(self: *Self, gpa: Allocator, string: []const u8) !u32 {
const gop = try self.table.getOrPutContextAdapted(gpa, @as([]const u8, string), StringIndexAdapter{
.bytes = &self.buffer,
}, StringIndexContext{
.bytes = &self.buffer,
});
if (gop.found_existing) {
const off = gop.key_ptr.*;
gop.value_ptr.* = true;
log.debug("reusing string '{s}' at offset 0x{x}", .{ string, off });
return off;
}
try self.buffer.ensureUnusedCapacity(gpa, string.len + 1);
const new_off = @as(u32, @intCast(self.buffer.items.len));
log.debug("writing new string '{s}' at offset 0x{x}", .{ string, new_off });
self.buffer.appendSliceAssumeCapacity(string);
self.buffer.appendAssumeCapacity(0);
gop.key_ptr.* = new_off;
gop.value_ptr.* = true;
return new_off;
}
pub fn delete(self: *Self, string: []const u8) void {
const value_ptr = self.table.getPtrAdapted(@as([]const u8, string), StringIndexAdapter{
.bytes = &self.buffer,
}) orelse return;
value_ptr.* = false;
log.debug("marked '{s}' for deletion", .{string});
}
pub fn getOffset(self: *Self, string: []const u8) ?u32 {
return self.table.getKeyAdapted(string, StringIndexAdapter{
.bytes = &self.buffer,
});
}
pub fn get(self: Self, off: u32) ?[]const u8 {
log.debug("getting string at 0x{x}", .{off});
if (off >= self.buffer.items.len) return null;
return mem.sliceTo(@as([*:0]const u8, @ptrCast(self.buffer.items.ptr + off)), 0);
}
pub fn getAssumeExists(self: Self, off: u32) []const u8 {
return self.get(off) orelse unreachable;
}
pub fn items(self: Self) []const u8 {
return self.buffer.items;
}
pub fn len(self: Self) usize {
return self.buffer.items.len;
}
};
}
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