From 0fcc7ea9b851ec3de3c26ef773a0f34e3ee97a15 Mon Sep 17 00:00:00 2001
From: Francis Le Roy <francis.leroy@protonmail.ch>
Date: Fri, 26 Feb 2021 17:35:45 +0100
Subject: [PATCH] Added 'build_with_params' function the visitor trait,
 allowing to build query from concatenations of queries

Updated changelog
---
 CHANGELOG.md            |  1 +
 src/visitor.rs          |  7 +++++++
 src/visitor/mssql.rs    | 19 ++++++++++++++-----
 src/visitor/mysql.rs    | 11 ++++++++++-
 src/visitor/postgres.rs | 11 ++++++++++-
 src/visitor/sqlite.rs   | 11 ++++++++++-
 6 files changed, 52 insertions(+), 8 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index ce39bfaea..5d930abcc 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -2,6 +2,7 @@
 ## Unreleased
 
 - Added support for `ROW_TO_JSON` function in postgresql
+- Added `build_with_params` function the `Visitor` trait
 
 ## v0.2.0-alpha.13
 
diff --git a/src/visitor.rs b/src/visitor.rs
index ba32cbd46..f7e29589b 100644
--- a/src/visitor.rs
+++ b/src/visitor.rs
@@ -65,6 +65,13 @@ pub trait Visitor<'a> {
     where
         Q: Into<Query<'a>>;
 
+    /// Behave exactly like [build](Visitor::build) but takes a vector of `Value<'a>` as arguments.
+    /// The next arguments to be inserted into the query will be **appended**, allowing to
+    /// build more complex queries.
+    fn build_with_params<Q>(query: Q, existing_params: Vec<Value<'a>>) -> crate::Result<(String, Vec<Value<'a>>)>
+    where
+        Q: Into<Query<'a>>;
+
     /// Write to the query.
     fn write<D: fmt::Display>(&mut self, s: D) -> Result;
 
diff --git a/src/visitor/mssql.rs b/src/visitor/mssql.rs
index a67ff309a..834d8b0af 100644
--- a/src/visitor/mssql.rs
+++ b/src/visitor/mssql.rs
@@ -128,17 +128,26 @@ impl<'a> Visitor<'a> for Mssql<'a> {
 
     fn build<Q>(query: Q) -> crate::Result<(String, Vec<Value<'a>>)>
     where
-        Q: Into<crate::ast::Query<'a>>,
+        Q: Into<Query<'a>>,
     {
-        let mut this = Mssql {
+        let params: Vec<Value<'a>> = Vec::with_capacity(128);
+
+        Self::build_with_params(query, params)
+    }
+
+    fn build_with_params<Q>(query: Q, existing_params: Vec<Value<'a>>) -> crate::Result<(String, Vec<Value<'a>>)>
+    where
+        Q: Into<Query<'a>>,
+    {
+        let mut mssql = Mssql {
             query: String::with_capacity(4096),
-            parameters: Vec::with_capacity(128),
+            parameters: existing_params,
             order_by_set: false,
         };
 
-        Mssql::visit_query(&mut this, query.into())?;
+        Mssql::visit_query(&mut mssql, query.into())?;
 
-        Ok((this.query, this.parameters))
+        Ok((mssql.query, mssql.parameters))
     }
 
     fn write<D: std::fmt::Display>(&mut self, s: D) -> visitor::Result {
diff --git a/src/visitor/mysql.rs b/src/visitor/mysql.rs
index cf97a491e..427f1b9bb 100644
--- a/src/visitor/mysql.rs
+++ b/src/visitor/mysql.rs
@@ -38,12 +38,21 @@ impl<'a> Visitor<'a> for Mysql<'a> {
     const C_WILDCARD: &'static str = "%";
 
     fn build<Q>(query: Q) -> crate::Result<(String, Vec<Value<'a>>)>
+    where
+        Q: Into<Query<'a>>,
+    {
+        let params: Vec<Value<'a>> = Vec::with_capacity(128);
+
+        Self::build_with_params(query, params)
+    }
+
+    fn build_with_params<Q>(query: Q, existing_params: Vec<Value<'a>>) -> crate::Result<(String, Vec<Value<'a>>)>
     where
         Q: Into<Query<'a>>,
     {
         let mut mysql = Mysql {
             query: String::with_capacity(4096),
-            parameters: Vec::with_capacity(128),
+            parameters: existing_params,
         };
 
         Mysql::visit_query(&mut mysql, query.into())?;
diff --git a/src/visitor/postgres.rs b/src/visitor/postgres.rs
index 5b1739e8a..b297318e9 100644
--- a/src/visitor/postgres.rs
+++ b/src/visitor/postgres.rs
@@ -20,12 +20,21 @@ impl<'a> Visitor<'a> for Postgres<'a> {
     const C_WILDCARD: &'static str = "%";
 
     fn build<Q>(query: Q) -> crate::Result<(String, Vec<Value<'a>>)>
+    where
+        Q: Into<Query<'a>>,
+    {
+        let params: Vec<Value<'a>> = Vec::with_capacity(128);
+
+        Self::build_with_params(query, params)
+    }
+
+    fn build_with_params<Q>(query: Q, existing_params: Vec<Value<'a>>) -> crate::Result<(String, Vec<Value<'a>>)>
     where
         Q: Into<Query<'a>>,
     {
         let mut postgres = Postgres {
             query: String::with_capacity(4096),
-            parameters: Vec::with_capacity(128),
+            parameters: existing_params,
         };
 
         Postgres::visit_query(&mut postgres, query.into())?;
diff --git a/src/visitor/sqlite.rs b/src/visitor/sqlite.rs
index 503dd6129..8bd02ab9b 100644
--- a/src/visitor/sqlite.rs
+++ b/src/visitor/sqlite.rs
@@ -22,12 +22,21 @@ impl<'a> Visitor<'a> for Sqlite<'a> {
     const C_WILDCARD: &'static str = "%";
 
     fn build<Q>(query: Q) -> crate::Result<(String, Vec<Value<'a>>)>
+    where
+        Q: Into<Query<'a>>,
+    {
+        let params: Vec<Value<'a>> = Vec::with_capacity(128);
+
+        Self::build_with_params(query, params)
+    }
+
+    fn build_with_params<Q>(query: Q, existing_params: Vec<Value<'a>>) -> crate::Result<(String, Vec<Value<'a>>)>
     where
         Q: Into<Query<'a>>,
     {
         let mut sqlite = Sqlite {
             query: String::with_capacity(4096),
-            parameters: Vec::with_capacity(128),
+            parameters: existing_params,
         };
 
         Sqlite::visit_query(&mut sqlite, query.into())?;