Merge 'bindings/javascript: Add pragma() support' from Anton Harniakou

This PR adds column names to the ouput of js pragma function.

Reviewed-by: Diego Reis (@el-yawd)
Reviewed-by: Jussi Saurio <jussi.saurio@gmail.com>

Closes #1608

core/lib.rs

@@ -789,7 +789,7 @@ impl Statement {
     }
 
     pub fn get_column_name(&self, idx: usize) -> Cow<str> {
-        let column = &self.program.result_columns[idx];
+        let column = &self.program.result_columns.get(idx).expect("No column");
         match column.name(&self.program.table_references) {
             Some(name) => Cow::Borrowed(name),
             None => Cow::Owned(column.expr.to_string()),

core/translate/pragma.rs

@@ -23,7 +23,7 @@ fn list_pragmas(program: &mut ProgramBuilder) {
         let register = program.emit_string8_new_reg(x.to_string());
         program.emit_result_row(register, 1);
     }
-
+    program.add_pragma_result_column("pragma_list".into());
     program.epilogue(crate::translate::emitter::TransactionMode::None);
 }
 
@@ -279,10 +279,12 @@ fn query_pragma(
                 register,
             );
             program.emit_result_row(register, 1);
+            program.add_pragma_result_column(pragma.to_string());
         }
         PragmaName::JournalMode => {
             program.emit_string8("wal".into(), register);
             program.emit_result_row(register, 1);
+            program.add_pragma_result_column(pragma.to_string());
         }
         PragmaName::LegacyFileFormat => {}
         PragmaName::WalCheckpoint => {
@@ -303,6 +305,7 @@ fn query_pragma(
                 dest: register,
             });
             program.emit_result_row(register, 1);
+            program.add_pragma_result_column(pragma.to_string());
         }
         PragmaName::TableInfo => {
             let table = match value {
@@ -348,6 +351,10 @@ fn query_pragma(
                     program.emit_result_row(base_reg, 6);
                 }
             }
+            let col_names = ["cid", "name", "type", "notnull", "dflt_value", "pk"];
+            for name in col_names {
+                program.add_pragma_result_column(name.into());
+            }
         }
         PragmaName::UserVersion => {
             program.emit_insn(Insn::ReadCookie {
@@ -355,6 +362,7 @@ fn query_pragma(
                 dest: register,
                 cookie: Cookie::UserVersion,
             });
+            program.add_pragma_result_column(pragma.to_string());
             program.emit_result_row(register, 1);
         }
         PragmaName::SchemaVersion => {
@@ -363,11 +371,13 @@ fn query_pragma(
                 dest: register,
                 cookie: Cookie::SchemaVersion,
             });
+            program.add_pragma_result_column(pragma.to_string());
             program.emit_result_row(register, 1);
         }
         PragmaName::PageSize => {
             program.emit_int(database_header.lock().get_page_size().into(), register);
             program.emit_result_row(register, 1);
+            program.add_pragma_result_column(pragma.to_string());
         }
         PragmaName::AutoVacuum => {
             let auto_vacuum_mode = pager.get_auto_vacuum_mode();

core/vdbe/builder.rs

@@ -285,6 +285,17 @@ impl ProgramBuilder {
         cursor
     }
 
+    pub fn add_pragma_result_column(&mut self, col_name: String) {
+        // TODO figure out a better type definition for ResultSetColumn
+        // or invent another way to set pragma result columns
+        let expr = ast::Expr::Id(ast::Id("".to_string()));
+        self.result_columns.push(ResultSetColumn {
+            expr,
+            alias: Some(col_name),
+            contains_aggregates: false,
+        });
+    }
+
     #[instrument(skip(self), level = Level::TRACE)]
     pub fn emit_insn(&mut self, insn: Insn) {
         let function = insn.to_function();