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const std = @import("std");
const jv = @import("../jv.zig");
const Instr = @import("./compile.zig").Instr;
pub const ExecuteError = error{
Unimplemented,
InvalidType,
InternalError,
};
const SaveableStack = @import("./saveable_stack.zig").SaveableStack;
const ValueStack = struct {
const Self = @This();
const Stack = SaveableStack(jv.Value);
stack: Stack,
pub fn init(allocator: std.mem.Allocator) !Self {
return .{
.stack = try Stack.init(allocator),
};
}
pub fn deinit(self: *Self) void {
self.stack.deinit();
}
pub fn push(self: *Self, value: jv.Value) !void {
try self.stack.push(value);
}
pub fn pop(self: *Self) jv.Value {
return self.stack.pop();
}
pub fn popInteger(self: *Self) ExecuteError!i64 {
const value = self.pop();
return switch (value) {
.integer => |i| i,
else => error.InvalidType,
};
}
pub fn popNumber(self: *Self) ExecuteError!f64 {
const value = self.pop();
return switch (value) {
.integer => |i| @floatFromInt(i),
.float => |f| f,
else => error.InvalidType,
};
}
pub fn popString(self: *Self) ExecuteError![]const u8 {
const value = self.pop();
return switch (value) {
.string => |s| s,
else => error.InvalidType,
};
}
pub fn popArray(self: *Self) ExecuteError!jv.Array {
const value = self.pop();
return switch (value) {
.array => |a| a,
else => error.InvalidType,
};
}
pub fn popObject(self: *Self) ExecuteError!jv.Object {
const value = self.pop();
return switch (value) {
.object => |o| o,
else => error.InvalidType,
};
}
pub fn dup(self: *Self) !void {
const top = self.stack.top().*;
try self.push(top);
}
pub fn swap(self: *Self) !void {
std.debug.assert(self.ensureSize(2));
const a = self.pop();
const b = self.pop();
try self.push(a);
try self.push(b);
}
pub fn save(self: *Self) !void {
try self.stack.save();
}
pub fn restore(self: *Self) void {
self.stack.restore();
}
pub fn ensureSize(self: *Self, n: usize) bool {
return self.stack.ensureSize(n);
}
};
pub const Runtime = struct {
const Self = @This();
values: ValueStack,
instrs: []const Instr,
input: jv.Value,
pc: usize,
pub fn init(allocator: std.mem.Allocator, instrs: []const Instr, input: jv.Value) !Self {
var self = Self{
.values = try ValueStack.init(allocator),
.instrs = instrs,
.input = input,
.pc = 0,
};
try self.values.push(input);
return self;
}
pub fn deinit(self: *Self) void {
self.values.deinit();
}
pub fn next(self: *Self) !?jv.Value {
while (self.pc < self.instrs.len) : (self.pc += 1) {
const cur = self.instrs[self.pc];
switch (cur) {
.nop => {},
.ret => {
self.pc += 1;
return self.values.pop();
},
.subexp_begin => try self.values.dup(),
.subexp_end => try self.values.swap(),
.array_index => {
std.debug.assert(self.values.ensureSize(2));
const array = try self.values.popArray();
const index: usize = @intCast(try self.values.popInteger());
const result = if (index < array.items.len) array.items[index] else .null;
try self.values.push(result);
},
.add => {
std.debug.assert(self.values.ensureSize(3));
_ = self.values.pop();
const lhs = try self.values.popInteger();
const rhs = try self.values.popInteger();
const result = lhs + rhs;
try self.values.push(.{ .integer = result });
},
.object_key => |key| {
std.debug.assert(self.values.ensureSize(1));
const obj = try self.values.popObject();
const result = obj.get(key) orelse .null;
try self.values.push(result);
},
.literal => |value| {
std.debug.assert(self.values.ensureSize(1));
_ = self.values.pop();
try self.values.push(value.*);
},
}
}
return null;
}
};
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