Merge pull request #143 from getty-zig/lifetimes-visitString-input

Introduce lifetime parameter to visitString
getty-zig · Sep 22, 2023 · 767c0cd · 767c0cd
2 parents 2118bce + bfb4d8f
commit 767c0cd
Show file tree

Hide file tree

Showing 17 changed files with 286 additions and 75 deletions.
diff --git a/src/de/blocks/slice.zig b/src/de/blocks/slice.zig
@@ -44,25 +44,31 @@ test "deserialize - slice, string" {
 
     const tests = .{
         .{
-            .name = "no sentinel",
+            .name = "no sentinel (copied)",
             .tokens = &.{.{ .String = "abc" }},
             .want = @as([]u8, &no_sentinel),
         },
         .{
-            .name = "no sentinel, const",
+            .name = "no sentinel, const (borrowed)",
             .tokens = &.{.{ .String = "abc" }},
             .want = @as([]const u8, &no_sentinel),
         },
         .{
-            .name = "sentinel",
-            .tokens = &.{.{ .String = "abc" }},
-            .want = @as([:0]u8, &sentinel),
+            .name = "sentinel (input has a sentinel)",
+            .tokens = &.{.{ .StringZ = "abc" }},
+            .want = @as([:0]const u8, &sentinel),
         },
         .{
-            .name = "sentinel, const",
+            .name = "sentinel, const (input has no sentinel)",
             .tokens = &.{.{ .String = "abc" }},
             .want = @as([:0]const u8, &sentinel),
         },
+        .{
+            .name = "sentinel (input has no sentinel, const -> mut)",
+            .tokens = &.{.{ .String = "abc" }},
+            .want = @as([:0]u8, &sentinel),
+        },
+        // TODO: Add test case for []u8 input to []const u8 output with and without sentinel.
     };
 
     inline for (tests) |t| {

diff --git a/src/de/de.zig b/src/de/de.zig
@@ -33,6 +33,13 @@ pub const de = struct {
     /// An implementation of `getty.de.Seed` that ignores values.
     pub const Ignored = @import("impls/seed/ignored.zig").Ignored;
 
+    /// The lifetime of the Getty String passed to a visitor's `visitString`
+    /// method.
+    pub const StringLifetime = @import("lifetime.zig").StringLifetime;
+
+    /// The lifetime of an access method's return value.
+    pub const ValueLifetime = @import("lifetime.zig").ValueLifetime;
+
     ////////////////////////////////////////////////////////////////////////////////
     // Namespaces
     ////////////////////////////////////////////////////////////////////////////////

diff --git a/src/de/impls/deserializer/content.zig b/src/de/impls/deserializer/content.zig
@@ -7,6 +7,7 @@ const getty_deserialize = @import("../../deserialize.zig").deserialize;
 const getty_error = @import("../../error.zig").Error;
 const MapAccessInterface = @import("../../interfaces/map_access.zig").MapAccess;
 const SeqAccessInterface = @import("../../interfaces/seq_access.zig").SeqAccess;
+const StringLifetime = @import("../../lifetime.zig").StringLifetime;
 const UnionAccessInterface = @import("../../interfaces/union_access.zig").UnionAccess;
 const VariantAccessInterface = @import("../../interfaces/variant_access.zig").VariantAccess;
 const VisitorInterface = @import("../../interfaces/visitor.zig").Visitor;
@@ -79,7 +80,7 @@ pub const ContentDeserializer = struct {
                 const int = v.to(@TypeOf(visitor).Value) catch unreachable;
                 break :blk try visitor.visitInt(ally, De, int);
             },
-            .String => |v| try visitor.visitString(ally, De, v),
+            .String => |v| try visitor.visitString(ally, De, v, .managed),
             else => error.InvalidType,
         };
     }
@@ -141,7 +142,7 @@ pub const ContentDeserializer = struct {
 
     fn deserializeString(self: Self, ally: std.mem.Allocator, visitor: anytype) getty_error!@TypeOf(visitor).Value {
         return switch (self.content) {
-            .String => |v| try visitor.visitString(ally, De, v),
+            .String => |v| try visitor.visitString(ally, De, v, .managed),
             else => error.InvalidType,
         };
     }

diff --git a/src/de/impls/visitor/array.zig b/src/de/impls/visitor/array.zig
@@ -1,5 +1,6 @@
 const std = @import("std");
 
+const StringLifetime = @import("../../lifetime.zig").StringLifetime;
 const VisitorInterface = @import("../../interfaces/visitor.zig").Visitor;
 
 pub fn Visitor(comptime Array: type) type {
@@ -17,7 +18,12 @@ pub fn Visitor(comptime Array: type) type {
 
         const Value = Array;
 
-        fn visitSeq(_: Self, ally: std.mem.Allocator, comptime Deserializer: type, seq: anytype) Deserializer.Err!Value {
+        fn visitSeq(
+            _: Self,
+            ally: std.mem.Allocator,
+            comptime Deserializer: type,
+            seq: anytype,
+        ) Deserializer.Err!Value {
             var array: Value = undefined;
             var seen: usize = 0;
 
@@ -42,17 +48,25 @@ pub fn Visitor(comptime Array: type) type {
             return array;
         }
 
-        fn visitString(_: Self, _: std.mem.Allocator, comptime Deserializer: type, input: anytype) Deserializer.Err!Value {
-            if (Child == u8) {
-                var string: Value = undefined;
+        fn visitString(
+            _: Self,
+            _: std.mem.Allocator,
+            comptime Deserializer: type,
+            input: anytype,
+            _: StringLifetime,
+        ) Deserializer.Err!Value {
+            if (Child != u8) {
+                return error.InvalidType;
+            }
+
+            var arr: Value = undefined;
 
-                if (input.len == string.len) {
-                    @memcpy(&string, input);
-                    return string;
-                }
+            if (input.len != arr.len) {
+                return error.InvalidLength;
             }
 
-            return error.InvalidType;
+            @memcpy(&arr, input);
+            return arr;
         }
 
         const Child = std.meta.Child(Value);

diff --git a/src/de/impls/visitor/content.zig b/src/de/impls/visitor/content.zig
@@ -3,6 +3,7 @@ const std = @import("std");
 const Content = @import("../../content.zig").Content;
 const ContentMultiArrayList = @import("../../content.zig").ContentMultiArrayList;
 const getty_deserialize = @import("../../deserialize.zig").deserialize;
+const StringLifetime = @import("../../lifetime.zig").StringLifetime;
 const VisitorInterface = @import("../../interfaces/visitor.zig").Visitor;
 
 const Visitor = @This();
@@ -87,11 +88,21 @@ fn visitSome(_: @This(), ally: std.mem.Allocator, deserializer: anytype) @TypeOf
     } };
 }
 
-fn visitString(_: @This(), ally: std.mem.Allocator, comptime Deserializer: type, input: anytype) Deserializer.Err!Content {
-    const output = try ally.alloc(u8, input.len);
-    std.mem.copy(u8, output, input);
-
-    return .{ .String = output };
+fn visitString(
+    _: @This(),
+    ally: std.mem.Allocator,
+    comptime Deserializer: type,
+    input: anytype,
+    lt: StringLifetime,
+) Deserializer.Err!Content {
+    switch (lt) {
+        .heap => return .{ .String = @as([]const u8, input) },
+        .stack, .managed => {
+            const copy = try ally.alloc(u8, input.len);
+            std.mem.copy(u8, copy, input);
+            return .{ .String = copy };
+        },
+    }
 }
 
 fn visitUnion(_: @This(), ally: std.mem.Allocator, comptime Deserializer: type, ua: anytype, va: anytype) Deserializer.Err!Content {

diff --git a/src/de/impls/visitor/enum.zig b/src/de/impls/visitor/enum.zig
@@ -1,6 +1,7 @@
 const std = @import("std");
 
 const getAttributes = @import("../../attributes.zig").getAttributes;
+const StringLifetime = @import("../../lifetime.zig").StringLifetime;
 const VisitorInterface = @import("../../interfaces/visitor.zig").Visitor;
 
 pub fn Visitor(comptime Enum: type) type {
@@ -18,7 +19,12 @@ pub fn Visitor(comptime Enum: type) type {
 
         const Value = Enum;
 
-        fn visitInt(_: Self, _: std.mem.Allocator, comptime Deserializer: type, input: anytype) Deserializer.Err!Value {
+        fn visitInt(
+            _: Self,
+            _: std.mem.Allocator,
+            comptime Deserializer: type,
+            input: anytype,
+        ) Deserializer.Err!Value {
             @setEvalBranchQuota(10_000);
 
             const fields = std.meta.fields(Value);
@@ -47,7 +53,13 @@ pub fn Visitor(comptime Enum: type) type {
             return e;
         }
 
-        fn visitString(_: Self, _: std.mem.Allocator, comptime Deserializer: type, input: anytype) Deserializer.Err!Value {
+        fn visitString(
+            _: Self,
+            _: std.mem.Allocator,
+            comptime Deserializer: type,
+            input: anytype,
+            _: StringLifetime,
+        ) Deserializer.Err!Value {
             @setEvalBranchQuota(10_000);
 
             const fields = std.meta.fields(Value);

diff --git a/src/de/impls/visitor/ignored.zig b/src/de/impls/visitor/ignored.zig
@@ -1,5 +1,6 @@
 const std = @import("std");
 
+const StringLifetime = @import("../../lifetime.zig").StringLifetime;
 const VisitorInterface = @import("../../interfaces/visitor.zig").Visitor;
 
 pub fn Visitor(comptime Ignored: type) type {
@@ -17,7 +18,7 @@ pub fn Visitor(comptime Ignored: type) type {
                 .visitNull = visitNothing,
                 .visitSeq = visitSeq,
                 .visitSome = visitSome,
-                .visitString = visitAny,
+                .visitString = visitString,
                 .visitUnion = visitUnion,
                 .visitVoid = visitNothing,
             },
@@ -53,6 +54,10 @@ pub fn Visitor(comptime Ignored: type) type {
             return .{};
         }
 
+        fn visitString(_: Self, _: std.mem.Allocator, comptime Deserializer: type, _: anytype, _: StringLifetime) Deserializer.Err!Value {
+            return .{};
+        }
+
         fn visitUnion(_: Self, _: std.mem.Allocator, comptime Deserializer: type, _: anytype, _: anytype) Deserializer.Err!Value {
             return .{};
         }

diff --git a/src/de/impls/visitor/net_address.zig b/src/de/impls/visitor/net_address.zig
@@ -1,5 +1,6 @@
 const std = @import("std");
 
+const StringLifetime = @import("../../lifetime.zig").StringLifetime;
 const VisitorInterface = @import("../../interfaces/visitor.zig").Visitor;
 
 pub fn Visitor(comptime NetAddress: type) type {
@@ -16,7 +17,13 @@ pub fn Visitor(comptime NetAddress: type) type {
 
         const Value = NetAddress;
 
-        fn visitString(_: Self, _: std.mem.Allocator, comptime Deserializer: type, input: anytype) Deserializer.Err!Value {
+        fn visitString(
+            _: Self,
+            _: ?std.mem.Allocator,
+            comptime Deserializer: type,
+            input: anytype,
+            _: StringLifetime,
+        ) Deserializer.Err!Value {
             const max_ipv6_chars = 47;
             const max_port_chars = 6;
 

diff --git a/src/de/impls/visitor/pointer.zig b/src/de/impls/visitor/pointer.zig
@@ -3,6 +3,8 @@ const std = @import("std");
 const blocks = @import("../../blocks.zig");
 const find_db = @import("../../find.zig").find_db;
 const has_attributes = @import("../../../attributes.zig").has_attributes;
+const StringLifetime = @import("../../lifetime.zig").StringLifetime;
+
 const VisitorInterface = @import("../../interfaces/visitor.zig").Visitor;
 
 pub fn Visitor(comptime Pointer: type) type {
@@ -103,12 +105,18 @@ pub fn Visitor(comptime Pointer: type) type {
             return value;
         }
 
-        fn visitString(_: Self, ally: std.mem.Allocator, comptime Deserializer: type, input: anytype) Deserializer.Err!Value {
+        fn visitString(
+            _: Self,
+            ally: std.mem.Allocator,
+            comptime Deserializer: type,
+            input: anytype,
+            lt: StringLifetime,
+        ) Deserializer.Err!Value {
             const value = try ally.create(Child);
             errdefer ally.destroy(value);
 
             var cv = ChildVisitor(Deserializer){};
-            value.* = try cv.visitor().visitString(ally, Deserializer, input);
+            value.* = try cv.visitor().visitString(ally, Deserializer, input, lt);
 
             return value;
         }

diff --git a/src/de/impls/visitor/semantic_version.zig b/src/de/impls/visitor/semantic_version.zig
@@ -1,5 +1,6 @@
 const std = @import("std");
 
+const StringLifetime = @import("../../lifetime.zig").StringLifetime;
 const VisitorInterface = @import("../../interfaces/visitor.zig").Visitor;
 
 const Visitor = @This();
@@ -14,18 +15,25 @@ pub usingnamespace VisitorInterface(
 
 const Value = std.SemanticVersion;
 
-fn visitString(_: Visitor, ally: std.mem.Allocator, comptime Deserializer: type, input: anytype) Deserializer.Err!Value {
+fn visitString(
+    _: Visitor,
+    ally: std.mem.Allocator,
+    comptime Deserializer: type,
+    input: anytype,
+    lt: StringLifetime,
+) Deserializer.Err!Value {
     var ver = std.SemanticVersion.parse(input) catch return error.InvalidValue;
 
-    if (ver.pre == null and ver.build == null) {
-        return ver;
-    }
+    switch (lt) {
+        .heap => {},
+        .stack, .managed => {
+            if (ver.pre == null and ver.build == null) {
+                return ver;
+            }
 
-    if (ver.pre) |pre| {
-        ver.pre = try ally.dupe(u8, pre);
-    }
-    if (ver.build) |build| {
-        ver.build = try ally.dupe(u8, build);
+            if (ver.pre) |pre| ver.pre = try ally.dupe(u8, pre);
+            if (ver.build) |build| ver.build = try ally.dupe(u8, build);
+        },
     }
 
     return ver;

diff --git a/src/de/impls/visitor/slice.zig b/src/de/impls/visitor/slice.zig
@@ -1,5 +1,6 @@
 const std = @import("std");
 
+const StringLifetime = @import("../../lifetime.zig").StringLifetime;
 const VisitorInterface = @import("../../interfaces/visitor.zig").Visitor;
 
 pub fn Visitor(comptime Slice: type) type {
@@ -33,17 +34,46 @@ pub fn Visitor(comptime Slice: type) type {
             return try list.toOwnedSlice();
         }
 
-        fn visitString(_: Self, ally: std.mem.Allocator, comptime Deserializer: type, input: anytype) Deserializer.Err!Value {
+        // input is only used directly if it the following are true:
+        //
+        //   1. input is a Heap value.
+        //   2. The sentinel values of input and Value match.
+        //   3. Either constness of input and Value match or are compatible
+        //      (i.e., Value is const and input is not const).
+        //
+        //  Otherwise, input is copied into a new slice.
+        fn visitString(
+            _: Self,
+            ally: std.mem.Allocator,
+            comptime Deserializer: type,
+            input: anytype,
+            lt: StringLifetime,
+        ) Deserializer.Err!Value {
             if (Child != u8) {
                 return error.InvalidType;
             }
 
-            const sentinel = @typeInfo(Value).Pointer.sentinel;
+            const v_info = @typeInfo(Value).Pointer;
 
-            const output = try ally.alloc(u8, input.len + @intFromBool(sentinel != null));
+            switch (lt) {
+                .heap => {
+                    const i_info = @typeInfo(@TypeOf(input)).Pointer;
+
+                    const sentinels_match = (v_info.sentinel == null) == (i_info.sentinel == null);
+                    const constness_match = v_info.is_const == i_info.is_const;
+                    const constness_compat = v_info.is_const and !i_info.is_const;
+
+                    if (sentinels_match and (constness_match or constness_compat)) {
+                        return @as(Value, input);
+                    }
+                },
+                .stack, .managed => {},
+            }
+
+            const output = try ally.alloc(u8, input.len + @intFromBool(v_info.sentinel != null));
             std.mem.copy(u8, output, input);
 
-            if (sentinel) |s| {
+            if (v_info.sentinel) |s| {
                 const sentinel_char = @as(*const u8, @ptrCast(s)).*;
                 output[input.len] = sentinel_char;
                 return output[0..input.len :sentinel_char];