pgrx_sql_entity_graph/schema/
mod.rs

1//LICENSE Portions Copyright 2019-2021 ZomboDB, LLC.
2//LICENSE
3//LICENSE Portions Copyright 2021-2023 Technology Concepts & Design, Inc.
4//LICENSE
5//LICENSE Portions Copyright 2023-2023 PgCentral Foundation, Inc. <contact@pgcentral.org>
6//LICENSE
7//LICENSE All rights reserved.
8//LICENSE
9//LICENSE Use of this source code is governed by the MIT license that can be found in the LICENSE file.
10/*!
11
12`#[pg_schema]` related macro expansion for Rust to SQL translation
13
14> Like all of the [`sql_entity_graph`][crate] APIs, this is considered **internal**
15> to the `pgrx` framework and very subject to change between versions. While you may use this, please do it with caution.
16
17*/
18pub mod entity;
19
20use proc_macro2::TokenStream as TokenStream2;
21use quote::{ToTokens, TokenStreamExt, quote};
22use syn::ItemMod;
23use syn::parse::{Parse, ParseStream};
24
25/// A parsed `#[pg_schema] mod example {}` item.
26///
27/// It should be used with [`syn::parse::Parse`] functions.
28///
29/// Using [`quote::ToTokens`] will output the declaration for a `pgrx::datum::pgrx_sql_entity_graph::InventorySchema`.
30///
31/// ```rust
32/// use syn::{Macro, parse::Parse, parse_quote, parse};
33/// use quote::{quote, ToTokens};
34/// use pgrx_sql_entity_graph::Schema;
35///
36/// # fn main() -> eyre::Result<()> {
37/// let parsed: Schema = parse_quote! {
38///     #[pg_schema] mod example {}
39/// };
40/// let entity_tokens = parsed.to_token_stream();
41/// # Ok(())
42/// # }
43/// ```
44#[derive(Debug, Clone)]
45pub struct Schema {
46    pub module: ItemMod,
47}
48
49impl Schema {
50    /*
51       It's necessary for `Schema` to handle the full `impl ToTokens` generation itself as the sql
52       entity graph code has to be inside the same `mod {}` that the `#[pg_schema]` macro is
53       attached to.
54
55       To facilitate that, we feature flag the `.entity_tokens()` function here to be a no-op if
56       the `no-schema-generation` feature flag is turned on
57    */
58
59    #[cfg(feature = "no-schema-generation")]
60    fn entity_tokens(&self) -> TokenStream2 {
61        quote! {}
62    }
63
64    #[cfg(not(feature = "no-schema-generation"))]
65    fn entity_tokens(&self) -> TokenStream2 {
66        let ident = &self.module.ident;
67        let postfix = {
68            use std::hash::{Hash, Hasher};
69
70            let (_content_brace, content_items) =
71                &self.module.content.as_ref().expect("Can only support `mod {}` right now.");
72
73            // A hack until https://github.com/rust-lang/rust/issues/54725 is fixed.
74            let mut hasher = std::collections::hash_map::DefaultHasher::new();
75            content_items.hash(&mut hasher);
76            hasher.finish()
77            // End of hack
78        };
79
80        let sql_graph_entity_fn_name = quote::format_ident!("__pgrx_schema_{ident}_{postfix}");
81        let payload_len = quote! {
82            ::pgrx::pgrx_sql_entity_graph::section::u8_len()
83                + ::pgrx::pgrx_sql_entity_graph::section::str_len(module_path!())
84                + ::pgrx::pgrx_sql_entity_graph::section::str_len(stringify!(#ident))
85                + ::pgrx::pgrx_sql_entity_graph::section::str_len(file!())
86                + ::pgrx::pgrx_sql_entity_graph::section::u32_len()
87        };
88        let total_len = quote! {
89            ::pgrx::pgrx_sql_entity_graph::section::u32_len() + (#payload_len)
90        };
91        quote! {
92            ::pgrx::pgrx_sql_entity_graph::__pgrx_schema_entry!(
93                #sql_graph_entity_fn_name,
94                #total_len,
95                ::pgrx::pgrx_sql_entity_graph::section::EntryWriter::<{ #total_len }>::new()
96                    .u32((#payload_len) as u32)
97                    .u8(::pgrx::pgrx_sql_entity_graph::section::ENTITY_SCHEMA)
98                    .str(module_path!())
99                    .str(stringify!(#ident))
100                    .str(file!())
101                    .u32(line!())
102                    .finish()
103            );
104        }
105    }
106}
107
108// We can't use the `CodeEnrichment` infrastructure, so we implement [`ToTokens`] directly
109impl ToTokens for Schema {
110    fn to_tokens(&self, tokens: &mut TokenStream2) {
111        let attrs = &self.module.attrs;
112        let vis = &self.module.vis;
113        let mod_token = &self.module.mod_token;
114        let ident = &self.module.ident;
115        let graph_tokens = self.entity_tokens(); // NB:  this could be an empty TokenStream if `no-schema-generation` is turned on
116
117        let (_content_brace, content_items) =
118            &self.module.content.as_ref().expect("Can only support `mod {}` right now.");
119
120        let code = quote! {
121            #(#attrs)*
122            #vis #mod_token #ident {
123                #(#content_items)*
124                #graph_tokens
125            }
126        };
127
128        tokens.append_all(code)
129    }
130}
131
132impl Parse for Schema {
133    fn parse(input: ParseStream) -> Result<Self, syn::Error> {
134        let module: ItemMod = input.parse()?;
135        crate::ident_is_acceptable_to_postgres(&module.ident)?;
136        Ok(Self { module })
137    }
138}
pgrx_sql_entity_graph/schema/mod.rs

pgrx_sql_entity_graph/schema/
mod.rs
