From b5a9dad9908f12d805d433cc31b9d1b27dcddc9f Mon Sep 17 00:00:00 2001
From: Louis Capitanchik <contact@louiscap.co>
Date: Tue, 16 May 2023 00:12:15 +0100
Subject: [PATCH] Support empty conditionals, assignment, variable
declarations, ident-as-value
---
forge-script-lang/src/parser/ast.rs | 12 +++++++++++
forge-script-lang/src/parser/grammar.rs | 20 ++++++++++++++-----
.../src/runtime/executor/printer.rs | 3 +++
3 files changed, 30 insertions(+), 5 deletions(-)
diff --git a/forge-script-lang/src/parser/ast.rs b/forge-script-lang/src/parser/ast.rs
index f6b8f55..739cacb 100644
--- a/forge-script-lang/src/parser/ast.rs
+++ b/forge-script-lang/src/parser/ast.rs
@@ -18,7 +18,18 @@ pub struct ExpressionList {
pub expressions: Vec<Expression>,
pub is_void: bool,
}
+impl Default for ExpressionList {
+ fn default() -> Self {
+ ExpressionList::empty()
+ }
+}
impl ExpressionList {
+ pub fn empty() -> Self {
+ ExpressionList {
+ expressions: Vec::new(),
+ is_void: true,
+ }
+ }
pub fn production(expressions: Vec<Expression>) -> Self {
ExpressionList {
expressions,
@@ -155,6 +166,7 @@ pub enum ValueExpression {
DeclareIdentifier(DeclareIdent),
Assignment(Assignment),
ConditionalBlock(Conditional),
+ Identifier(Identifier),
}
#[derive(Clone)]
diff --git a/forge-script-lang/src/parser/grammar.rs b/forge-script-lang/src/parser/grammar.rs
index 9e5fdba..30cbd86 100644
--- a/forge-script-lang/src/parser/grammar.rs
+++ b/forge-script-lang/src/parser/grammar.rs
@@ -29,19 +29,26 @@ peg::parser! {
rule value_expression() -> ValueExpression
= "(" ex:value_expression() ")" { ValueExpression::Grouped(GroupedExpression { inner: Box::new(ex) }) }
/ co:conditional() { ValueExpression::ConditionalBlock(co) }
+ / decl:declare_variable() { ValueExpression::DeclareIdentifier(decl) }
/ left:value_expression() op:binary_operator() right:value_expression()
{ ValueExpression::Binary { lhs: Box::new(left), rhs: Box::new(right), operator: op } }
/ op:unary_operator() operand:value_expression()
{ ValueExpression::Unary { operator: op, operand: Box::new(operand) } }
+ / ident:bare_identifier() { ValueExpression::Identifier(ident) }
/ li:literal() { ValueExpression::Literal(li) }
rule print() -> Print
= "print" ex:value_expression() { ex.into() }
+ rule declare_variable() -> DeclareIdent
+ = "let" assign:assignment() { DeclareIdent::WithValue(assign) }
+ / "let" ident:bare_identifier() { DeclareIdent::WithoutValue(ident) }
+
rule condition_loop() -> ConditionalLoop
- = "while" guard:value_expression() "{" block:expression_list() "}" { ConditionalLoop { block: GuardedBlock { guard: Box::new(guard), block}, fallback: None } }
- / "while" guard:value_expression() "{" block:expression_list() "}" "else" "{" fallback:expression_list() "}"
- { ConditionalLoop { block: GuardedBlock { guard: Box::new(guard), block}, fallback: Some(fallback) } }
+ = "while" guard:value_expression() "{" block:expression_list()? "}"
+ { ConditionalLoop { block: GuardedBlock { guard: Box::new(guard), block: block.unwrap_or_default() }, fallback: None } }
+ / "while" guard:value_expression() "{" block:expression_list()? "}" "else" "{" fallback:expression_list()? "}"
+ { ConditionalLoop { block: GuardedBlock { guard: Box::new(guard), block: block.unwrap_or_default() }, fallback } }
rule conditional() -> Conditional
// = bl:guarded_block() { Conditional { fallback: None, blocks: vec![bl] } }
@@ -54,8 +61,11 @@ peg::parser! {
/ blocks:(guarded_block() ++ "else") { Conditional { fallback: None, blocks, } }
rule guarded_block() -> GuardedBlock
- = "if" guard:value_expression() "{" block:expression_list() "}"
- { GuardedBlock { block, guard: Box::new(guard) } }
+ = "if" guard:value_expression() "{" block:expression_list()? "}"
+ { GuardedBlock { block: block.unwrap_or_default(), guard: Box::new(guard) } }
+
+ rule assignment() -> Assignment
+ = ident:bare_identifier() "=" expr:value_expression() { Assignment { ident, value: Box::new(expr) } }
rule binary_operator() -> BinaryOp
= "+" { BinaryOp::Add }
diff --git a/forge-script-lang/src/runtime/executor/printer.rs b/forge-script-lang/src/runtime/executor/printer.rs
index 7431492..0c05b5d 100644
--- a/forge-script-lang/src/runtime/executor/printer.rs
+++ b/forge-script-lang/src/runtime/executor/printer.rs
@@ -140,6 +140,9 @@ impl Visitor for TreePrinter {
self.evaluate_value_expression(inner.as_ref());
self.write(")");
}
+ ValueExpression::Identifier(ident) => {
+ self.write(ident);
+ }
}
}
--
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