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Streamline switch case AST structure.

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This commit is contained in:
Stephen Chung 2022-07-19 13:33:53 +08:00
parent 281e94fc62
commit 5149c56256
6 changed files with 98 additions and 135 deletions
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4
src/ast/mod.rs
View File

@ -22,8 +22,8 @@ pub use script_fn::EncapsulatedEnviron;
#[cfg(not(feature = "no_function"))]
pub use script_fn::{ScriptFnDef, ScriptFnMetadata};
pub use stmt::{
CaseBlocksList, ConditionalStmtBlock, OpAssignment, RangeCase, Stmt, StmtBlock,
StmtBlockContainer, SwitchCasesCollection, TryCatchBlock,
CaseBlocksList, ConditionalExpr, OpAssignment, RangeCase, Stmt, StmtBlock, StmtBlockContainer,
SwitchCasesCollection, TryCatchBlock,
};
#[cfg(not(feature = "no_float"))]

67
src/ast/stmt.rs
View File

@ -122,39 +122,39 @@ impl fmt::Debug for OpAssignment {
}
}
/// A statements block with a condition.
/// An expression with a condition.
///
/// The condition may simply be [`Expr::BoolConstant`] with `true` if there is actually no condition.
#[derive(Debug, Clone, Default, Hash)]
pub struct ConditionalStmtBlock {
pub struct ConditionalExpr {
/// Condition.
pub condition: Expr,
/// Statements block.
pub statements: StmtBlock,
/// Expression.
pub expr: Expr,
}
impl<B: Into<StmtBlock>> From<B> for ConditionalStmtBlock {
impl<E: Into<Expr>> From<E> for ConditionalExpr {
#[inline(always)]
fn from(value: B) -> Self {
fn from(value: E) -> Self {
Self {
condition: Expr::BoolConstant(true, Position::NONE),
statements: value.into(),
expr: value.into(),
}
}
}
impl<B: Into<StmtBlock>> From<(Expr, B)> for ConditionalStmtBlock {
impl<E: Into<Expr>> From<(Expr, E)> for ConditionalExpr {
#[inline(always)]
fn from(value: (Expr, B)) -> Self {
fn from(value: (Expr, E)) -> Self {
Self {
condition: value.0,
statements: value.1.into(),
expr: value.1.into(),
}
}
}
impl ConditionalStmtBlock {
/// Is this conditional statements block always `true`?
impl ConditionalExpr {
/// Is the condition always `true`?
#[inline(always)]
#[must_use]
pub fn is_always_true(&self) -> bool {
@ -163,7 +163,7 @@ impl ConditionalStmtBlock {
_ => false,
}
}
/// Is this conditional statements block always `false`?
/// Is the condition always `false`?
#[inline(always)]
#[must_use]
pub fn is_always_false(&self) -> bool {
@ -283,9 +283,9 @@ pub type CaseBlocksList = smallvec::SmallVec<[usize; 1]>;
/// Exported under the `internals` feature only.
#[derive(Debug, Clone, Hash)]
pub struct SwitchCasesCollection {
/// List of [`ConditionalStmtBlock`]'s.
pub case_blocks: StaticVec<ConditionalStmtBlock>,
/// Dictionary mapping value hashes to [`ConditionalStmtBlock`]'s.
/// List of [`ConditionalExpr`]'s.
pub expressions: StaticVec<ConditionalExpr>,
/// Dictionary mapping value hashes to [`ConditionalExpr`]'s.
pub cases: BTreeMap<u64, CaseBlocksList>,
/// List of range cases.
pub ranges: StaticVec<RangeCase>,
@ -779,18 +779,15 @@ impl Stmt {
let (expr, sw) = &**x;
expr.is_pure()
&& sw.cases.values().flat_map(|cases| cases.iter()).all(|&c| {
let block = &sw.case_blocks[c];
block.condition.is_pure() && block.statements.iter().all(Stmt::is_pure)
let block = &sw.expressions[c];
block.condition.is_pure() && block.expr.is_pure()
})
&& sw.ranges.iter().all(|r| {
let block = &sw.case_blocks[r.index()];
block.condition.is_pure() && block.statements.iter().all(Stmt::is_pure)
let block = &sw.expressions[r.index()];
block.condition.is_pure() && block.expr.is_pure()
})
&& sw.def_case.is_some()
&& sw.case_blocks[sw.def_case.unwrap()]
.statements
.iter()
.all(Stmt::is_pure)
&& sw.expressions[sw.def_case.unwrap()].expr.is_pure()
}
// Loops that exit can be pure because it can never be infinite.
@ -933,35 +930,29 @@ impl Stmt {
}
for (.., blocks) in &sw.cases {
for &b in blocks {
let block = &sw.case_blocks[b];
let block = &sw.expressions[b];
if !block.condition.walk(path, on_node) {
return false;
}
for s in &block.statements {
if !s.walk(path, on_node) {
return false;
}
if !block.expr.walk(path, on_node) {
return false;
}
}
}
for r in &sw.ranges {
let block = &sw.case_blocks[r.index()];
let block = &sw.expressions[r.index()];
if !block.condition.walk(path, on_node) {
return false;
}
for s in &block.statements {
if !s.walk(path, on_node) {
return false;
}
if !block.expr.walk(path, on_node) {
return false;
}
}
if let Some(index) = sw.def_case {
for s in &sw.case_blocks[index].statements {
if !s.walk(path, on_node) {
return false;
}
if !sw.expressions[index].expr.walk(path, on_node) {
return false;
}
}
}

37
src/eval/stmt.rs
View File

@ -394,7 +394,7 @@ impl Engine {
let (
expr,
SwitchCasesCollection {
case_blocks,
expressions,
cases,
def_case,
ranges,
@ -405,7 +405,7 @@ impl Engine {
self.eval_expr(scope, global, caches, lib, this_ptr, expr, level);
if let Ok(value) = value_result {
let stmt_block_result = if value.is_hashable() {
let expr_result = if value.is_hashable() {
let hasher = &mut get_hasher();
value.hash(hasher);
let hash = hasher.finish();
@ -417,7 +417,7 @@ impl Engine {
let mut result = Ok(None);
for &index in case_blocks_list {
let block = &case_blocks[index];
let block = &expressions[index];
let cond_result = match block.condition {
Expr::BoolConstant(b, ..) => Ok(b),
@ -435,7 +435,7 @@ impl Engine {
match cond_result {
Ok(true) => {
result = Ok(Some(&block.statements));
result = Ok(Some(&block.expr));
break;
}
Ok(false) => (),
@ -453,7 +453,7 @@ impl Engine {
let mut result = Ok(None);
for r in ranges.iter().filter(|r| r.contains(value)) {
let block = &case_blocks[r.index()];
let block = &expressions[r.index()];
let cond_result = match block.condition {
Expr::BoolConstant(b, ..) => Ok(b),
@ -470,7 +470,7 @@ impl Engine {
};
match cond_result {
Ok(true) => result = Ok(Some(&block.statements)),
Ok(true) => result = Ok(Some(&block.expr)),
Ok(false) => continue,
_ => result = cond_result.map(|_| None),
}
@ -488,31 +488,18 @@ impl Engine {
Ok(None)
};
if let Ok(Some(statements)) = stmt_block_result {
if !statements.is_empty() {
self.eval_stmt_block(
scope, global, caches, lib, this_ptr, statements, true, level,
)
} else {
Ok(Dynamic::UNIT)
}
} else if let Ok(None) = stmt_block_result {
if let Ok(Some(expr)) = expr_result {
self.eval_expr(scope, global, caches, lib, this_ptr, expr, level)
} else if let Ok(None) = expr_result {
// Default match clause
if let Some(index) = def_case {
let def_case = &case_blocks[*index].statements;
if !def_case.is_empty() {
self.eval_stmt_block(
scope, global, caches, lib, this_ptr, def_case, true, level,
)
} else {
Ok(Dynamic::UNIT)
}
let def_expr = &expressions[*index].expr;
self.eval_expr(scope, global, caches, lib, this_ptr, def_expr, level)
} else {
Ok(Dynamic::UNIT)
}
} else {
stmt_block_result.map(|_| Dynamic::UNIT)
expr_result.map(|_| Dynamic::UNIT)
}
} else {
value_result

2
src/lib.rs
View File

@ -284,7 +284,7 @@ pub use parser::ParseState;
#[cfg(feature = "internals")]
pub use ast::{
ASTFlags, ASTNode, BinaryExpr, ConditionalStmtBlock, Expr, FnCallExpr, FnCallHashes, Ident,
ASTFlags, ASTNode, BinaryExpr, ConditionalExpr, Expr, FnCallExpr, FnCallHashes, Ident,
OpAssignment, RangeCase, ScriptFnDef, Stmt, StmtBlock, SwitchCasesCollection, TryCatchBlock,
};

108
src/optimizer.rs
View File

@ -527,7 +527,7 @@ fn optimize_stmt(stmt: &mut Stmt, state: &mut OptimizerState, preserve_result: b
let (
match_expr,
SwitchCasesCollection {
case_blocks,
expressions,
cases,
ranges,
def_case,
@ -544,26 +544,23 @@ fn optimize_stmt(stmt: &mut Stmt, state: &mut OptimizerState, preserve_result: b
match &case_blocks_list[..] {
[] => (),
[index] => {
let mut b = mem::take(&mut case_blocks[*index]);
let mut b = mem::take(&mut expressions[*index]);
cases.clear();
if b.is_always_true() {
// Promote the matched case
let statements: StmtBlockContainer = mem::take(&mut b.statements);
let statements =
optimize_stmt_block(statements, state, true, true, false);
*stmt = (statements, b.statements.span()).into();
let mut statements = Stmt::Expr(mem::take(&mut b.expr).into());
optimize_stmt(&mut statements, state, true);
*stmt = statements;
} else {
// switch const { case if condition => stmt, _ => def } => if condition { stmt } else { def }
optimize_expr(&mut b.condition, state, false);
let else_stmt = if let Some(index) = def_case {
let def_case = &mut case_blocks[*index].statements;
let def_span = def_case.span_or_else(*pos, Position::NONE);
let def_case: StmtBlockContainer = mem::take(def_case);
let def_stmt =
optimize_stmt_block(def_case, state, true, true, false);
StmtBlock::new_with_span(def_stmt, def_span)
let mut def_stmt =
Stmt::Expr(mem::take(&mut expressions[*index].expr).into());
optimize_stmt(&mut def_stmt, state, true);
def_stmt.into()
} else {
StmtBlock::NONE
};
@ -571,7 +568,7 @@ fn optimize_stmt(stmt: &mut Stmt, state: &mut OptimizerState, preserve_result: b
*stmt = Stmt::If(
(
mem::take(&mut b.condition),
mem::take(&mut b.statements),
Stmt::Expr(mem::take(&mut b.expr).into()).into(),
else_stmt,
)
.into(),
@ -584,14 +581,13 @@ fn optimize_stmt(stmt: &mut Stmt, state: &mut OptimizerState, preserve_result: b
}
_ => {
for &index in case_blocks_list {
let mut b = mem::take(&mut case_blocks[index]);
let mut b = mem::take(&mut expressions[index]);
if b.is_always_true() {
// Promote the matched case
let statements: StmtBlockContainer = mem::take(&mut b.statements);
let statements =
optimize_stmt_block(statements, state, true, true, false);
*stmt = (statements, b.statements.span()).into();
let mut statements = Stmt::Expr(mem::take(&mut b.expr).into());
optimize_stmt(&mut statements, state, true);
*stmt = statements;
state.set_dirty();
return;
}
@ -608,18 +604,17 @@ fn optimize_stmt(stmt: &mut Stmt, state: &mut OptimizerState, preserve_result: b
if ranges.len() == 1
|| ranges
.iter()
.all(|r| case_blocks[r.index()].is_always_true())
.all(|r| expressions[r.index()].is_always_true())
{
for r in ranges.iter().filter(|r| r.contains(value)) {
let range_block = &mut case_blocks[r.index()];
let range_block = &mut expressions[r.index()];
if range_block.is_always_true() {
// Promote the matched case
let block = &mut case_blocks[r.index()];
let statements = mem::take(&mut *block.statements);
let statements =
optimize_stmt_block(statements, state, true, true, false);
*stmt = (statements, block.statements.span()).into();
let block = &mut expressions[r.index()];
let mut statements = Stmt::Expr(mem::take(&mut block.expr).into());
optimize_stmt(&mut statements, state, true);
*stmt = statements;
} else {
let mut condition = mem::take(&mut range_block.condition);
@ -627,20 +622,20 @@ fn optimize_stmt(stmt: &mut Stmt, state: &mut OptimizerState, preserve_result: b
optimize_expr(&mut condition, state, false);
let else_stmt = if let Some(index) = def_case {
let def_case = &mut case_blocks[*index].statements;
let def_span = def_case.span_or_else(*pos, Position::NONE);
let def_case: StmtBlockContainer = mem::take(def_case);
let def_stmt =
optimize_stmt_block(def_case, state, true, true, false);
StmtBlock::new_with_span(def_stmt, def_span)
let mut def_stmt =
Stmt::Expr(mem::take(&mut expressions[*index].expr).into());
optimize_stmt(&mut def_stmt, state, true);
def_stmt.into()
} else {
StmtBlock::NONE
};
let statements = mem::take(&mut case_blocks[r.index()].statements);
let if_stmt =
Stmt::Expr(mem::take(&mut expressions[r.index()].expr).into())
.into();
*stmt = Stmt::If(
(condition, statements, else_stmt).into(),
(condition, if_stmt, else_stmt).into(),
match_expr.start_position(),
);
}
@ -664,12 +659,9 @@ fn optimize_stmt(stmt: &mut Stmt, state: &mut OptimizerState, preserve_result: b
}
for r in &*ranges {
let b = &mut case_blocks[r.index()];
let statements = mem::take(&mut *b.statements);
*b.statements =
optimize_stmt_block(statements, state, preserve_result, true, false);
let b = &mut expressions[r.index()];
optimize_expr(&mut b.condition, state, false);
optimize_expr(&mut b.expr, state, false);
}
return;
}
@ -679,11 +671,9 @@ fn optimize_stmt(stmt: &mut Stmt, state: &mut OptimizerState, preserve_result: b
state.set_dirty();
if let Some(index) = def_case {
let def_case = &mut case_blocks[*index].statements;
let def_span = def_case.span_or_else(*pos, Position::NONE);
let def_case: StmtBlockContainer = mem::take(def_case);
let def_stmt = optimize_stmt_block(def_case, state, true, true, false);
*stmt = (def_stmt, def_span).into();
let mut def_stmt = Stmt::Expr(mem::take(&mut expressions[*index].expr).into());
optimize_stmt(&mut def_stmt, state, true);
*stmt = def_stmt;
} else {
*stmt = StmtBlock::empty(*pos).into();
}
@ -693,7 +683,7 @@ fn optimize_stmt(stmt: &mut Stmt, state: &mut OptimizerState, preserve_result: b
let (
match_expr,
SwitchCasesCollection {
case_blocks,
expressions,
cases,
ranges,
def_case,
@ -704,16 +694,13 @@ fn optimize_stmt(stmt: &mut Stmt, state: &mut OptimizerState, preserve_result: b
optimize_expr(match_expr, state, false);
// Optimize blocks
for b in case_blocks.iter_mut() {
let statements = mem::take(&mut *b.statements);
*b.statements =
optimize_stmt_block(statements, state, preserve_result, true, false);
for b in expressions.iter_mut() {
optimize_expr(&mut b.condition, state, false);
optimize_expr(&mut b.expr, state, false);
if b.is_always_false() {
if !b.statements.is_empty() {
b.statements = StmtBlock::NONE;
if !b.expr.is_unit() {
b.expr = Expr::Unit(b.expr.position());
state.set_dirty();
}
}
@ -723,7 +710,7 @@ fn optimize_stmt(stmt: &mut Stmt, state: &mut OptimizerState, preserve_result: b
cases.retain(|_, list| {
// Remove all entries that have false conditions
list.retain(|index| {
if case_blocks[*index].is_always_false() {
if expressions[*index].is_always_false() {
state.set_dirty();
false
} else {
@ -733,7 +720,7 @@ fn optimize_stmt(stmt: &mut Stmt, state: &mut OptimizerState, preserve_result: b
// Remove all entries after a `true` condition
if let Some(n) = list
.iter()
.find(|&&index| case_blocks[index].is_always_true())
.find(|&&index| expressions[index].is_always_true())
{
if n + 1 < list.len() {
state.set_dirty();
@ -752,7 +739,7 @@ fn optimize_stmt(stmt: &mut Stmt, state: &mut OptimizerState, preserve_result: b
// Remove false ranges
ranges.retain(|r| {
if case_blocks[r.index()].is_always_false() {
if expressions[r.index()].is_always_false() {
state.set_dirty();
false
} else {
@ -761,14 +748,11 @@ fn optimize_stmt(stmt: &mut Stmt, state: &mut OptimizerState, preserve_result: b
});
if let Some(index) = def_case {
let def_stmt_block = &mut case_blocks[*index].statements;
let def_block = mem::take(&mut **def_stmt_block);
**def_stmt_block =
optimize_stmt_block(def_block, state, preserve_result, true, false);
optimize_expr(&mut expressions[*index].expr, state, false);
}
// Remove unused block statements
for index in 0..case_blocks.len() {
for index in 0..expressions.len() {
if *def_case == Some(index)
|| cases.values().flat_map(|c| c.iter()).any(|&n| n == index)
|| ranges.iter().any(|r| r.index() == index)
@ -776,10 +760,10 @@ fn optimize_stmt(stmt: &mut Stmt, state: &mut OptimizerState, preserve_result: b
continue;
}
let b = &mut case_blocks[index];
let b = &mut expressions[index];
if !b.statements.is_empty() {
b.statements = StmtBlock::NONE;
if !b.expr.is_unit() {
b.expr = Expr::Unit(b.expr.position());
state.set_dirty();
}
}

15
src/parser.rs
View File

@ -3,9 +3,9 @@
use crate::api::events::VarDefInfo;
use crate::api::options::LangOptions;
use crate::ast::{
ASTFlags, BinaryExpr, CaseBlocksList, ConditionalStmtBlock, Expr, FnCallExpr, FnCallHashes,
Ident, OpAssignment, RangeCase, ScriptFnDef, Stmt, StmtBlockContainer, SwitchCasesCollection,
TryCatchBlock,
ASTFlags, BinaryExpr, CaseBlocksList, ConditionalExpr, Expr, FnCallExpr, FnCallHashes, Ident,
OpAssignment, RangeCase, ScriptFnDef, Stmt, StmtBlock, StmtBlockContainer,
SwitchCasesCollection, TryCatchBlock,
};
use crate::engine::{Precedence, KEYWORD_THIS, OP_CONTAINS};
use crate::eval::GlobalRuntimeState;
@ -1055,7 +1055,7 @@ impl Engine {
}
}
let mut case_blocks = StaticVec::<ConditionalStmtBlock>::new();
let mut expressions = StaticVec::<ConditionalExpr>::new();
let mut cases = BTreeMap::<u64, CaseBlocksList>::new();
let mut ranges = StaticVec::<RangeCase>::new();
let mut def_case = None;
@ -1142,8 +1142,9 @@ impl Engine {
let need_comma = !stmt.is_self_terminated();
let has_condition = !matches!(condition, Expr::BoolConstant(true, ..));
case_blocks.push((condition, stmt).into());
let index = case_blocks.len() - 1;
let stmt_block: StmtBlock = stmt.into();
expressions.push((condition, Expr::Stmt(stmt_block.into())).into());
let index = expressions.len() - 1;
if !case_expr_list.is_empty() {
for expr in case_expr_list {
@ -1224,7 +1225,7 @@ impl Engine {
}
let cases = SwitchCasesCollection {
case_blocks,
expressions,
cases,
def_case,
ranges,