1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167

//LICENSE Portions Copyright 2019-2021 ZomboDB, LLC.
//LICENSE
//LICENSE Portions Copyright 2021-2023 Technology Concepts & Design, Inc.
//LICENSE
//LICENSE Portions Copyright 2023-2023 PgCentral Foundation, Inc. <contact@pgcentral.org>
//LICENSE
//LICENSE All rights reserved.
//LICENSE
//LICENSE Use of this source code is governed by the MIT license that can be found in the LICENSE file.
/*!

`#[pg_trigger]` related macro expansion for Rust to SQL translation

> Like all of the [`sql_entity_graph`][crate::pgrx_sql_entity_graph] APIs, this is considered **internal**
to the `pgrx` framework and very subject to change between versions. While you may use this, please do it with caution.

*/
pub mod attribute;
pub mod entity;

use crate::enrich::{ToEntityGraphTokens, ToRustCodeTokens};
use crate::{CodeEnrichment, ToSqlConfig};
use attribute::PgTriggerAttribute;
use proc_macro2::{Span, TokenStream as TokenStream2};
use quote::quote;
use syn::{ItemFn, Token};

#[derive(Debug, Clone)]
pub struct PgTrigger {
    func: syn::ItemFn,
    to_sql_config: ToSqlConfig,
}

impl PgTrigger {
    pub fn new(
        func: ItemFn,
        attributes: syn::punctuated::Punctuated<PgTriggerAttribute, Token![,]>,
    ) -> Result<CodeEnrichment<Self>, syn::Error> {
        if attributes.len() > 1 {
            return Err(syn::Error::new(
                Span::call_site(),
                "Multiple `sql` arguments found, it must be unique",
            ));
        };
        let to_sql_config = attributes
            .first()
            .cloned()
            .map(|PgTriggerAttribute::Sql(mut config)| {
                if let Some(ref mut content) = config.content {
                    let value = content.value();
                    let updated_value = value
                        .replace("@FUNCTION_NAME@", &*(func.sig.ident.to_string() + "_wrapper"))
                        + "\n";
                    *content = syn::LitStr::new(&updated_value, Span::call_site());
                };
                config
            })
            .unwrap_or_default();

        if !to_sql_config.overrides_default() {
            crate::ident_is_acceptable_to_postgres(&func.sig.ident)?;
        }

        Ok(CodeEnrichment(PgTrigger { func, to_sql_config }))
    }

    pub fn wrapper_tokens(&self) -> Result<ItemFn, syn::Error> {
        let function_ident = &self.func.sig.ident;
        let extern_func_ident = syn::Ident::new(
            &format!("{}_wrapper", self.func.sig.ident.to_string()),
            self.func.sig.ident.span(),
        );
        let tokens = quote! {
            #[no_mangle]
            #[::pgrx::pgrx_macros::pg_guard]
            unsafe extern "C" fn #extern_func_ident(fcinfo: ::pgrx::pg_sys::FunctionCallInfo) -> ::pgrx::pg_sys::Datum {
                let fcinfo_ref = unsafe {
                    // SAFETY:  The caller should be Postgres in this case and it will give us a valid "fcinfo" pointer
                    fcinfo.as_ref().expect("fcinfo was NULL from Postgres")
                };
                let maybe_pg_trigger = unsafe { ::pgrx::trigger_support::PgTrigger::from_fcinfo(fcinfo_ref) };
                let pg_trigger = maybe_pg_trigger.expect("PgTrigger::from_fcinfo failed");
                let trigger_fn_result: Result<
                    Option<::pgrx::heap_tuple::PgHeapTuple<'_, _>>,
                    _,
                > = #function_ident(&pg_trigger);


                // The trigger "protocol" allows a function to return the null pointer, but NOT to
                // set the isnull result flag.  This is why we return `Datum::from(0)` in the None cases
                let trigger_retval = trigger_fn_result.expect("Trigger function panic");
                match trigger_retval {
                    None => unsafe { ::pgrx::pg_sys::Datum::from(0) },
                    Some(trigger_retval) => match trigger_retval.into_trigger_datum() {
                        None => unsafe { ::pgrx::pg_sys::Datum::from(0) },
                        Some(datum) => datum,
                    }
                }
            }

        };
        syn::parse2(tokens)
    }

    pub fn finfo_tokens(&self) -> Result<ItemFn, syn::Error> {
        let finfo_name = syn::Ident::new(
            &format!("pg_finfo_{}_wrapper", self.func.sig.ident),
            proc_macro2::Span::call_site(),
        );
        let tokens = quote! {
            #[no_mangle]
            #[doc(hidden)]
            pub extern "C" fn #finfo_name() -> &'static ::pgrx::pg_sys::Pg_finfo_record {
                const V1_API: ::pgrx::pg_sys::Pg_finfo_record = ::pgrx::pg_sys::Pg_finfo_record { api_version: 1 };
                &V1_API
            }
        };
        syn::parse2(tokens)
    }
}

impl ToEntityGraphTokens for PgTrigger {
    fn to_entity_graph_tokens(&self) -> TokenStream2 {
        let sql_graph_entity_fn_name = syn::Ident::new(
            &format!("__pgrx_internals_trigger_{}", self.func.sig.ident.to_string()),
            self.func.sig.ident.span(),
        );
        let func_sig_ident = &self.func.sig.ident;
        let function_name = func_sig_ident.to_string();
        let to_sql_config = &self.to_sql_config;

        quote! {
            #[no_mangle]
            #[doc(hidden)]
            #[allow(unknown_lints, clippy::no_mangle_with_rust_abi)]
            pub extern "Rust" fn #sql_graph_entity_fn_name() -> ::pgrx::pgrx_sql_entity_graph::SqlGraphEntity {
                use core::any::TypeId;
                extern crate alloc;
                use alloc::vec::Vec;
                use alloc::vec;
                let submission = ::pgrx::pgrx_sql_entity_graph::PgTriggerEntity {
                    function_name: #function_name,
                    file: file!(),
                    line: line!(),
                    full_path: concat!(module_path!(), "::", stringify!(#func_sig_ident)),
                    module_path: module_path!(),
                    to_sql_config: #to_sql_config,
                };
                ::pgrx::pgrx_sql_entity_graph::SqlGraphEntity::Trigger(submission)
            }
        }
    }
}

impl ToRustCodeTokens for PgTrigger {
    fn to_rust_code_tokens(&self) -> TokenStream2 {
        let wrapper_func = self.wrapper_tokens().expect("Generating wrappper function for trigger");
        let finfo_func = self.finfo_tokens().expect("Generating finfo function for trigger");
        let func = &self.func;

        quote! {
            #func
            #wrapper_func
            #finfo_func
        }
    }
}