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Switch Statement to std::variant (#639)

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Aligns Assign/Assignment, If/IfStatement naming to favor the name in the enum.
This commit is contained in:
Jon Meow
2021-07-13 13:54:38 -07:00
committed by GitHub
parent b03d3cdbb0
commit 0960c51d20
5 changed files with 156 additions and 147 deletions
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executable_semantics/ast/statement.h
+64 -37
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@@ -30,68 +30,96 @@ enum class StatementKind {
struct Statement;
struct Assignment {
struct ExpressionStatement {
static constexpr StatementKind Kind = StatementKind::ExpressionStatement;
const Expression* exp;
};
struct Assign {
static constexpr StatementKind Kind = StatementKind::Assign;
const Expression* lhs;
const Expression* rhs;
};
struct VariableDefinition {
static constexpr StatementKind Kind = StatementKind::VariableDefinition;
const Expression* pat;
const Expression* init;
};
struct IfStatement {
struct If {
static constexpr StatementKind Kind = StatementKind::If;
const Expression* cond;
const Statement* then_stmt;
const Statement* else_stmt;
};
struct Return {
static constexpr StatementKind Kind = StatementKind::Return;
const Expression* exp;
};
struct Sequence {
static constexpr StatementKind Kind = StatementKind::Sequence;
const Statement* stmt;
const Statement* next;
};
struct Block {
static constexpr StatementKind Kind = StatementKind::Block;
const Statement* stmt;
};
struct While {
static constexpr StatementKind Kind = StatementKind::While;
const Expression* cond;
const Statement* body;
};
struct Break {
static constexpr StatementKind Kind = StatementKind::Break;
};
struct Continue {
static constexpr StatementKind Kind = StatementKind::Continue;
};
struct Match {
static constexpr StatementKind Kind = StatementKind::Match;
const Expression* exp;
std::list<std::pair<const Expression*, const Statement*>>* clauses;
};
struct Continuation {
std::string* continuation_variable;
static constexpr StatementKind Kind = StatementKind::Continuation;
std::string continuation_variable;
const Statement* body;
};
struct Run {
static constexpr StatementKind Kind = StatementKind::Run;
const Expression* argument;
};
struct Statement {
// TODO: change Statement to a class and make all members private
int line_num;
StatementKind tag;
struct Await {
static constexpr StatementKind Kind = StatementKind::Await;
};
struct Statement {
// Constructors
static auto MakeExpStmt(int line_num, const Expression* exp)
static auto MakeExpressionStatement(int line_num, const Expression* exp)
-> const Statement*;
static auto MakeAssign(int line_num, const Expression* lhs,
const Expression* rhs) -> const Statement*;
static auto MakeVarDef(int line_num, const Expression* pat,
const Expression* init) -> const Statement*;
static auto MakeVariableDefinition(int line_num, const Expression* pat,
const Expression* init)
-> const Statement*;
static auto MakeIf(int line_num, const Expression* cond,
const Statement* then_stmt, const Statement* else_stmt)
-> const Statement*;
static auto MakeReturn(int line_num, const Expression* e) -> const Statement*;
static auto MakeSeq(int line_num, const Statement* s1, const Statement* s2)
-> const Statement*;
static auto MakeSequence(int line_num, const Statement* s1,
const Statement* s2) -> const Statement*;
static auto MakeBlock(int line_num, const Statement* s) -> const Statement*;
static auto MakeWhile(int line_num, const Expression* cond,
const Statement* body) -> const Statement*;
@@ -119,33 +147,32 @@ struct Statement {
// __await;
static auto MakeAwait(int line_num) -> const Statement*;
// Access to the alternatives
const Expression* GetExpression() const;
Assignment GetAssign() const;
VariableDefinition GetVariableDefinition() const;
IfStatement GetIf() const;
const Expression* GetReturn() const;
Sequence GetSequence() const;
Block GetBlock() const;
While GetWhile() const;
Match GetMatch() const;
Continuation GetContinuation() const;
Run GetRun() const;
auto GetExpressionStatement() const -> const ExpressionStatement&;
auto GetAssign() const -> const Assign&;
auto GetVariableDefinition() const -> const VariableDefinition&;
auto GetIf() const -> const If&;
auto GetReturn() const -> const Return&;
auto GetSequence() const -> const Sequence&;
auto GetBlock() const -> const Block&;
auto GetWhile() const -> const While&;
auto GetBreak() const -> const Break&;
auto GetContinue() const -> const Continue&;
auto GetMatch() const -> const Match&;
auto GetContinuation() const -> const Continuation&;
auto GetRun() const -> const Run&;
auto GetAwait() const -> const Await&;
inline auto tag() const -> StatementKind {
return std::visit([](const auto& t) { return t.Kind; }, value);
}
int line_num;
private:
union {
const Expression* exp;
Assignment assign;
VariableDefinition variable_definition;
IfStatement if_stmt;
const Expression* return_stmt;
Sequence sequence;
Block block;
While while_stmt;
Match match_stmt;
Continuation continuation;
Run run;
} u;
std::variant<ExpressionStatement, Assign, VariableDefinition, If, Return,
Sequence, Block, While, Break, Continue, Match, Continuation,
Run, Await>
value;
};
void PrintStatement(const Statement*, int);