From a7cc367c1ffb82df5a801b235cdc1df6f9c7d64b Mon Sep 17 00:00:00 2001
From: Glauber Costa <glauber@turso.tech>
Date: Thu, 30 Jan 2025 21:05:31 -0500
Subject: [PATCH] implement pragma pragma_list

List all available pragmas (Except pragma_list)
---
 COMPAT.md             |  2 +-
 Cargo.lock            | 25 +++++++++++++++++++++++++
 core/Cargo.toml       |  1 +
 core/translate/mod.rs | 37 +++++++++++++++++++++++++++++++++++++
 4 files changed, 64 insertions(+), 1 deletion(-)

diff --git a/COMPAT.md b/COMPAT.md
index fb2da2d79..905de6c77 100644
--- a/COMPAT.md
+++ b/COMPAT.md
@@ -138,7 +138,7 @@ The current status of Limbo is:
 | PRAGMA page_count                | No         |                                              |
 | PRAGMA page_size                 | No         |                                              |
 | PRAGMA parser_trace              | No         |                                              |
-| PRAGMA pragma_list               | No         |                                              |
+| PRAGMA pragma_list               | Yes        |                                              |
 | PRAGMA query_only                | No         |                                              |
 | PRAGMA quick_check               | No         |                                              |
 | PRAGMA read_uncommitted          | No         |                                              |
diff --git a/Cargo.lock b/Cargo.lock
index af303d953..23a263f9c 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -1588,6 +1588,7 @@ dependencies = [
  "serde",
  "sieve-cache",
  "sqlite3-parser",
+ "strum",
  "tempfile",
  "thiserror 1.0.69",
 ]
@@ -2704,6 +2705,8 @@ dependencies = [
  "phf",
  "phf_codegen",
  "phf_shared",
+ "strum",
+ "strum_macros",
  "uncased",
 ]
 
@@ -2731,6 +2734,28 @@ version = "0.11.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "7da8b5736845d9f2fcb837ea5d9e2628564b3b043a70948a3f0b778838c5fb4f"
 
+[[package]]
+name = "strum"
+version = "0.26.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "8fec0f0aef304996cf250b31b5a10dee7980c85da9d759361292b8bca5a18f06"
+dependencies = [
+ "strum_macros",
+]
+
+[[package]]
+name = "strum_macros"
+version = "0.26.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "4c6bee85a5a24955dc440386795aa378cd9cf82acd5f764469152d2270e581be"
+dependencies = [
+ "heck",
+ "proc-macro2",
+ "quote",
+ "rustversion",
+ "syn 2.0.96",
+]
+
 [[package]]
 name = "supports-color"
 version = "3.0.2"
diff --git a/core/Cargo.toml b/core/Cargo.toml
index 347602f57..d2172af34 100644
--- a/core/Cargo.toml
+++ b/core/Cargo.toml
@@ -66,6 +66,7 @@ limbo_vector = { path = "../extensions/vector", optional = true, features = ["st
 limbo_regexp = { path = "../extensions/regexp", optional = true, features = ["static"] }
 limbo_percentile = { path = "../extensions/percentile", optional = true, features = ["static"] }
 miette = "7.4.0"
+strum = "0.26"
 
 [build-dependencies]
 chrono = "0.4.38"
diff --git a/core/translate/mod.rs b/core/translate/mod.rs
index 04e0e3af2..c0190942b 100644
--- a/core/translate/mod.rs
+++ b/core/translate/mod.rs
@@ -29,6 +29,7 @@ use crate::storage::wal::CheckpointMode;
 use crate::translate::delete::translate_delete;
 use crate::util::{normalize_ident, PRIMARY_KEY_AUTOMATIC_INDEX_NAME_PREFIX};
 use crate::vdbe::builder::CursorType;
+use crate::vdbe::BranchOffset;
 use crate::vdbe::{builder::ProgramBuilder, insn::Insn, Program};
 use crate::{bail_parse_error, Connection, LimboError, Result, SymbolTable};
 use insert::translate_insert;
@@ -38,6 +39,7 @@ use std::cell::RefCell;
 use std::fmt::Display;
 use std::rc::{Rc, Weak};
 use std::str::FromStr;
+use strum::IntoEnumIterator;
 
 /// Translate SQL statement into bytecode program.
 pub fn translate(
@@ -531,6 +533,36 @@ enum PrimaryKeyDefinitionType<'a> {
     Composite,
 }
 
+fn list_pragmas(
+    program: &mut ProgramBuilder,
+    init_label: BranchOffset,
+    start_offset: BranchOffset,
+) {
+    let mut pragma_strings: Vec<String> = PragmaName::iter().map(|x| x.to_string()).collect();
+    pragma_strings.sort();
+
+    let register = program.alloc_register();
+    for pragma in &pragma_strings {
+        program.emit_insn(Insn::String8 {
+            value: pragma.to_string(),
+            dest: register,
+        });
+        program.emit_insn(Insn::ResultRow {
+            start_reg: register,
+            count: 1,
+        });
+    }
+    program.emit_insn(Insn::Halt {
+        err_code: 0,
+        description: String::new(),
+    });
+    program.resolve_label(init_label, program.offset());
+    program.emit_constant_insns();
+    program.emit_insn(Insn::Goto {
+        target_pc: start_offset,
+    });
+}
+
 fn translate_pragma(
     program: &mut ProgramBuilder,
     schema: &Schema,
@@ -546,6 +578,11 @@ fn translate_pragma(
     let start_offset = program.offset();
     let mut write = false;
 
+    if name.name.0.to_lowercase() == "pragma_list" {
+        list_pragmas(program, init_label, start_offset);
+        return Ok(());
+    }
+
     let pragma = match PragmaName::from_str(&name.name.0) {
         Ok(pragma) => pragma,
         Err(_) => bail_parse_error!("Not a valid pragma name"),