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::{format_ident, quote, ToTokens, TokenStreamExt};
22use syn::parse::{Parse, ParseStream};
23use syn::ItemMod;
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 =
81            format_ident!("__pgrx_internals_schema_{}_{}", ident, postfix);
82        quote! {
83            #[no_mangle]
84            #[doc(hidden)]
85            #[allow(unknown_lints, clippy::no_mangle_with_rust_abi)]
86            pub extern "Rust" fn  #sql_graph_entity_fn_name() -> ::pgrx::pgrx_sql_entity_graph::SqlGraphEntity {
87                extern crate alloc;
88                use alloc::vec::Vec;
89                use alloc::vec;
90                let submission = ::pgrx::pgrx_sql_entity_graph::SchemaEntity {
91                        module_path: module_path!(),
92                        name: stringify!(#ident),
93                        file: file!(),
94                        line: line!(),
95                    };
96                ::pgrx::pgrx_sql_entity_graph::SqlGraphEntity::Schema(submission)
97            }
98        }
99    }
100}
101
102// We can't use the `CodeEnrichment` infrastructure, so we implement [`ToTokens`] directly
103impl ToTokens for Schema {
104    fn to_tokens(&self, tokens: &mut TokenStream2) {
105        let attrs = &self.module.attrs;
106        let vis = &self.module.vis;
107        let mod_token = &self.module.mod_token;
108        let ident = &self.module.ident;
109        let graph_tokens = self.entity_tokens(); // NB:  this could be an empty TokenStream if `no-schema-generation` is turned on
110
111        let (_content_brace, content_items) =
112            &self.module.content.as_ref().expect("Can only support `mod {}` right now.");
113
114        let code = quote! {
115            #(#attrs)*
116            #vis #mod_token #ident {
117                #(#content_items)*
118                #graph_tokens
119            }
120        };
121
122        tokens.append_all(code)
123    }
124}
125
126impl Parse for Schema {
127    fn parse(input: ParseStream) -> Result<Self, syn::Error> {
128        let module: ItemMod = input.parse()?;
129        crate::ident_is_acceptable_to_postgres(&module.ident)?;
130        Ok(Self { module })
131    }
132}
pgrx_sql_entity_graph/schema/mod.rs

pgrx_sql_entity_graph/schema/
mod.rs
