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Lorenzo Torres 2025-12-16 14:21:41 +01:00
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zig-out/
.zig-cache/

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const std = @import("std");
// Although this function looks imperative, it does not perform the build
// directly and instead it mutates the build graph (`b`) that will be then
// executed by an external runner. The functions in `std.Build` implement a DSL
// for defining build steps and express dependencies between them, allowing the
// build runner to parallelize the build automatically (and the cache system to
// know when a step doesn't need to be re-run).
pub fn build(b: *std.Build) void {
// Standard target options allow the person running `zig build` to choose
// what target to build for. Here we do not override the defaults, which
// means any target is allowed, and the default is native. Other options
// for restricting supported target set are available.
const target = b.standardTargetOptions(.{});
// Standard optimization options allow the person running `zig build` to select
// between Debug, ReleaseSafe, ReleaseFast, and ReleaseSmall. Here we do not
// set a preferred release mode, allowing the user to decide how to optimize.
const optimize = b.standardOptimizeOption(.{});
// It's also possible to define more custom flags to toggle optional features
// of this build script using `b.option()`. All defined flags (including
// target and optimize options) will be listed when running `zig build --help`
// in this directory.
// This creates a module, which represents a collection of source files alongside
// some compilation options, such as optimization mode and linked system libraries.
// Zig modules are the preferred way of making Zig code available to consumers.
// addModule defines a module that we intend to make available for importing
// to our consumers. We must give it a name because a Zig package can expose
// multiple modules and consumers will need to be able to specify which
// module they want to access.
const mod = b.addModule("al", .{
// The root source file is the "entry point" of this module. Users of
// this module will only be able to access public declarations contained
// in this file, which means that if you have declarations that you
// intend to expose to consumers that were defined in other files part
// of this module, you will have to make sure to re-export them from
// the root file.
.root_source_file = b.path("src/root.zig"),
// Later on we'll use this module as the root module of a test executable
// which requires us to specify a target.
.target = target,
});
// Here we define an executable. An executable needs to have a root module
// which needs to expose a `main` function. While we could add a main function
// to the module defined above, it's sometimes preferable to split business
// logic and the CLI into two separate modules.
//
// If your goal is to create a Zig library for others to use, consider if
// it might benefit from also exposing a CLI tool. A parser library for a
// data serialization format could also bundle a CLI syntax checker, for example.
//
// If instead your goal is to create an executable, consider if users might
// be interested in also being able to embed the core functionality of your
// program in their own executable in order to avoid the overhead involved in
// subprocessing your CLI tool.
//
// If neither case applies to you, feel free to delete the declaration you
// don't need and to put everything under a single module.
const exe = b.addExecutable(.{
.name = "al",
.root_module = b.createModule(.{
// b.createModule defines a new module just like b.addModule but,
// unlike b.addModule, it does not expose the module to consumers of
// this package, which is why in this case we don't have to give it a name.
.root_source_file = b.path("src/main.zig"),
// Target and optimization levels must be explicitly wired in when
// defining an executable or library (in the root module), and you
// can also hardcode a specific target for an executable or library
// definition if desireable (e.g. firmware for embedded devices).
.target = target,
.optimize = optimize,
// List of modules available for import in source files part of the
// root module.
.imports = &.{
// Here "al" is the name you will use in your source code to
// import this module (e.g. `@import("al")`). The name is
// repeated because you are allowed to rename your imports, which
// can be extremely useful in case of collisions (which can happen
// importing modules from different packages).
.{ .name = "al", .module = mod },
},
}),
});
// This declares intent for the executable to be installed into the
// install prefix when running `zig build` (i.e. when executing the default
// step). By default the install prefix is `zig-out/` but can be overridden
// by passing `--prefix` or `-p`.
b.installArtifact(exe);
// This creates a top level step. Top level steps have a name and can be
// invoked by name when running `zig build` (e.g. `zig build run`).
// This will evaluate the `run` step rather than the default step.
// For a top level step to actually do something, it must depend on other
// steps (e.g. a Run step, as we will see in a moment).
const run_step = b.step("run", "Run the app");
// This creates a RunArtifact step in the build graph. A RunArtifact step
// invokes an executable compiled by Zig. Steps will only be executed by the
// runner if invoked directly by the user (in the case of top level steps)
// or if another step depends on it, so it's up to you to define when and
// how this Run step will be executed. In our case we want to run it when
// the user runs `zig build run`, so we create a dependency link.
const run_cmd = b.addRunArtifact(exe);
run_step.dependOn(&run_cmd.step);
// By making the run step depend on the default step, it will be run from the
// installation directory rather than directly from within the cache directory.
run_cmd.step.dependOn(b.getInstallStep());
// This allows the user to pass arguments to the application in the build
// command itself, like this: `zig build run -- arg1 arg2 etc`
if (b.args) |args| {
run_cmd.addArgs(args);
}
// Creates an executable that will run `test` blocks from the provided module.
// Here `mod` needs to define a target, which is why earlier we made sure to
// set the releative field.
const mod_tests = b.addTest(.{
.root_module = mod,
});
// A run step that will run the test executable.
const run_mod_tests = b.addRunArtifact(mod_tests);
// Creates an executable that will run `test` blocks from the executable's
// root module. Note that test executables only test one module at a time,
// hence why we have to create two separate ones.
const exe_tests = b.addTest(.{
.root_module = exe.root_module,
});
// A run step that will run the second test executable.
const run_exe_tests = b.addRunArtifact(exe_tests);
// A top level step for running all tests. dependOn can be called multiple
// times and since the two run steps do not depend on one another, this will
// make the two of them run in parallel.
const test_step = b.step("test", "Run tests");
test_step.dependOn(&run_mod_tests.step);
test_step.dependOn(&run_exe_tests.step);
// Just like flags, top level steps are also listed in the `--help` menu.
//
// The Zig build system is entirely implemented in userland, which means
// that it cannot hook into private compiler APIs. All compilation work
// orchestrated by the build system will result in other Zig compiler
// subcommands being invoked with the right flags defined. You can observe
// these invocations when one fails (or you pass a flag to increase
// verbosity) to validate assumptions and diagnose problems.
//
// Lastly, the Zig build system is relatively simple and self-contained,
// and reading its source code will allow you to master it.
}

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.{
// This is the default name used by packages depending on this one. For
// example, when a user runs `zig fetch --save <url>`, this field is used
// as the key in the `dependencies` table. Although the user can choose a
// different name, most users will stick with this provided value.
//
// It is redundant to include "zig" in this name because it is already
// within the Zig package namespace.
.name = .al,
// This is a [Semantic Version](https://semver.org/).
// In a future version of Zig it will be used for package deduplication.
.version = "0.0.0",
// Together with name, this represents a globally unique package
// identifier. This field is generated by the Zig toolchain when the
// package is first created, and then *never changes*. This allows
// unambiguous detection of one package being an updated version of
// another.
//
// When forking a Zig project, this id should be regenerated (delete the
// field and run `zig build`) if the upstream project is still maintained.
// Otherwise, the fork is *hostile*, attempting to take control over the
// original project's identity. Thus it is recommended to leave the comment
// on the following line intact, so that it shows up in code reviews that
// modify the field.
.fingerprint = 0x793b656ad110237c, // Changing this has security and trust implications.
// Tracks the earliest Zig version that the package considers to be a
// supported use case.
.minimum_zig_version = "0.15.2",
// This field is optional.
// Each dependency must either provide a `url` and `hash`, or a `path`.
// `zig build --fetch` can be used to fetch all dependencies of a package, recursively.
// Once all dependencies are fetched, `zig build` no longer requires
// internet connectivity.
.dependencies = .{
// See `zig fetch --save <url>` for a command-line interface for adding dependencies.
//.example = .{
// // When updating this field to a new URL, be sure to delete the corresponding
// // `hash`, otherwise you are communicating that you expect to find the old hash at
// // the new URL. If the contents of a URL change this will result in a hash mismatch
// // which will prevent zig from using it.
// .url = "https://example.com/foo.tar.gz",
//
// // This is computed from the file contents of the directory of files that is
// // obtained after fetching `url` and applying the inclusion rules given by
// // `paths`.
// //
// // This field is the source of truth; packages do not come from a `url`; they
// // come from a `hash`. `url` is just one of many possible mirrors for how to
// // obtain a package matching this `hash`.
// //
// // Uses the [multihash](https://multiformats.io/multihash/) format.
// .hash = "...",
//
// // When this is provided, the package is found in a directory relative to the
// // build root. In this case the package's hash is irrelevant and therefore not
// // computed. This field and `url` are mutually exclusive.
// .path = "foo",
//
// // When this is set to `true`, a package is declared to be lazily
// // fetched. This makes the dependency only get fetched if it is
// // actually used.
// .lazy = false,
//},
},
// Specifies the set of files and directories that are included in this package.
// Only files and directories listed here are included in the `hash` that
// is computed for this package. Only files listed here will remain on disk
// when using the zig package manager. As a rule of thumb, one should list
// files required for compilation plus any license(s).
// Paths are relative to the build root. Use the empty string (`""`) to refer to
// the build root itself.
// A directory listed here means that all files within, recursively, are included.
.paths = .{
"build.zig",
"build.zig.zon",
"src",
// For example...
//"LICENSE",
//"README.md",
},
}

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#!/bin/bash
zig build run 2>&1 >/dev/null | dot -Tpdf -o graph.pdf
zathura graph.pdf
rm graph.pdf

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const std = @import("std");
const Lexer = @This();
index: usize,
source: []u8,
start: usize,
pub const TokenType = enum {
plus,
minus,
star,
slash,
integer,
float,
identifier,
eof,
illegal,
};
pub const Token = struct {
@"type": TokenType,
lexeme: []u8,
};
pub fn parseSpecial(lexer: *Lexer) Token {
var token_type: TokenType = .eof;
switch (lexer.source[lexer.index]) {
'+' => token_type = .plus,
'-' => token_type = .minus,
'*' => token_type = .star,
'/' => token_type = .slash,
else => token_type = .eof,
}
lexer.index += 1;
return .{
.@"type" = token_type,
.lexeme = undefined,
};
}
pub fn next(lexer: *Lexer) Token {
lexer.skipWhitespaceAndComments();
if (lexer.index >= lexer.source.len) {
return lexer.makeToken(.eof);
}
const c = lexer.source[lexer.index];
// Numbers
if (std.ascii.isDigit(c)) {
return lexer.number();
}
// Identifiers
if (std.ascii.isAlphabetic(c)) {
}
// Single Character Tokens
lexer.index += 1;
switch (c) {
'+' => return lexer.makeToken(.plus),
'-' => return lexer.makeToken(.minus),
'*' => return lexer.makeToken(.star),
'/' => return lexer.makeToken(.slash),
else => return lexer.makeToken(.illegal),
}
}
fn makeToken(lexer: *Lexer, @"type": TokenType) Token {
return .{
.@"type" = @"type",
// Safely slice the source
.lexeme = if (lexer.index <= lexer.source.len)
lexer.source[lexer.start..lexer.index]
else
"",
};
}
fn skipWhitespaceAndComments(lexer: *Lexer) void {
while (lexer.index < lexer.source.len) {
const c = lexer.source[lexer.index];
switch (c) {
// Whitespace
' ', '\t', '\r', '\n' => {
lexer.index += 1;
},
// Comments
'#' => {
while (lexer.index < lexer.source.len and lexer.source[lexer.index] != '\n') {
lexer.index += 1;
}
},
else => {
lexer.start = lexer.index;
return;
}
}
}
}
fn number(lexer: *Lexer) Token {
while (lexer.index < lexer.source.len and std.ascii.isDigit(lexer.source[lexer.index])) {
lexer.index += 1;
}
if (lexer.index < lexer.source.len and lexer.source[lexer.index] == '.') {
if (lexer.index + 1 < lexer.source.len and std.ascii.isDigit(lexer.source[lexer.index + 1])) {
lexer.index += 1; // consume dot
while (lexer.index < lexer.source.len and std.ascii.isDigit(lexer.source[lexer.index])) {
lexer.index += 1;
}
return lexer.makeToken(.float);
}
}
return lexer.makeToken(.integer);
}
/// If `source` was allocated on the heap,
/// the caller must free it.
pub fn init(source: []u8) Lexer {
return .{
.index = 0,
.source = source,
.start = 0,
};
}

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const std = @import("std");
const Lexer = @import("Lexer.zig");
const Parser = @This();
lexer: *Lexer,
allocator: std.mem.Allocator,
node_table: std.AutoHashMap(u64, *Node),
previous: Lexer.Token,
current: Lexer.Token,
pub const NodeType = enum {
add,
sub,
mul,
div,
integer,
float,
start,
@"return",
};
pub const Node = struct {
@"type": NodeType,
id: u64,
inputs: std.ArrayList(*Node),
outputs: std.ArrayList(*Node),
data: extern union {
integer: u64,
float: f64,
},
pub fn init(parser: *Parser, @"type": NodeType) !*Node {
var node = try parser.allocator.create(Node);
node.@"type" = @"type";
node.inputs = .{};
node.outputs = .{};
node.data = undefined;
return node;
}
pub fn globalNumbering(node: *Node, parser: *Parser) !*Node {
const node_hash = node.hash();
node.id = node_hash;
if (parser.node_table.get(node_hash)) |n| {
parser.allocator.destroy(node);
return n;
}
try parser.node_table.put(node_hash, node);
return node;
}
pub fn hash(node: *Node) u64 {
var hasher = std.hash.Wyhash.init(0);
std.hash.autoHash(&hasher, node.@"type");
switch (node.@"type") {
.integer => std.hash.autoHash(&hasher, node.data.integer),
.float => std.hash.autoHash(&hasher, @as(u64, @bitCast(node.data.float))),
else => {},
}
for (node.inputs.items) |n| {
std.hash.autoHash(&hasher, @intFromPtr(n));
}
return hasher.final();
}
pub fn deinit(node: *Node, parser: *Parser) void {
parser.allocator.destroy(node);
}
};
pub fn match(parser: *Parser, expected: Lexer.TokenType) bool {
if (parser.current.@"type" == expected) {
parser.advance();
return true;
}
return false;
}
pub fn advance(parser: *Parser) void {
parser.previous = parser.current;
parser.current = parser.lexer.next();
}
pub fn buildFactor(parser: *Parser) !?*Node {
const token = parser.current;
switch (token.@"type") {
.integer => {
parser.advance();
const node = try Node.init(parser, .integer);
node.data.integer = std.fmt.parseInt(u64, token.lexeme, 10) catch 0;
return node.globalNumbering(parser);
},
.float => {
parser.advance();
const node = try Node.init(parser, .float);
node.data.float = std.fmt.parseFloat(f64, token.lexeme) catch 0;
return node.globalNumbering(parser);
},
else => {}
}
return null;
}
pub fn buildTerm(parser: *Parser) !?*Node {
var lhs = try parser.buildFactor();
while (parser.match(.star) or parser.match(.slash)) {
const node_type: NodeType = switch (parser.previous.@"type") {
.star => .mul,
.slash => .div,
else => unreachable,
};
var node = try Node.init(parser, node_type);
try node.inputs.append(parser.allocator, (try parser.buildFactor()).?);
try node.inputs.append(parser.allocator, lhs.?);
node = try node.globalNumbering(parser);
lhs = node;
}
return lhs;
}
pub fn buildExpression(parser: *Parser) !?*Node {
var lhs = try parser.buildTerm();
while (parser.match(.plus) or parser.match(.minus)) {
const node_type: NodeType = switch (parser.previous.@"type") {
.plus => .add,
.minus => .sub,
else => unreachable,
};
var node = try Node.init(parser, node_type);
try node.inputs.append(parser.allocator, (try parser.buildTerm()).?);
try node.inputs.append(parser.allocator, lhs.?);
node = try node.globalNumbering(parser);
lhs = node;
}
return lhs;
}
pub fn buildGraph(parser: *Parser) !?*Node {
return try buildExpression(parser);
}
pub fn init(allocator: std.mem.Allocator, lexer: *Lexer) Parser {
var parser: Parser = .{
.lexer = lexer,
.allocator = allocator,
.node_table = std.AutoHashMap(u64, *Node).init(allocator),
.previous = undefined,
.current = undefined,
};
parser.advance();
return parser;
}
pub fn deinit(parser: *Parser) void {
parser.node_table.deinit();
}

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const std = @import("std");
const al = @import("al");
pub fn nodeName(node: *al.Parser.Node) void {
switch (node.@"type") {
.start => std.debug.print("{d} [label=\"start\",fillcolor=yellow, color=black, shape=box]", .{node.id}),
.add => std.debug.print("{d} [label=\"+\"]", .{node.id}),
.sub => std.debug.print("{d} [label=\"-\"]", .{node.id}),
.mul => std.debug.print("{d} [label=\"*\"]", .{node.id}),
.div => std.debug.print("{d} [label=\"/\"]", .{node.id}),
.integer => std.debug.print("{d} [label=\"{d}\"]", .{node.id, node.data.integer}),
.float => std.debug.print("{d} [label=\"{d}\"]", .{node.id, node.data.float}),
else => {},
}
std.debug.print("\n", .{});
}
pub fn printGraph(node: *al.Parser.Node) void {
for (node.inputs.items) |n| {
nodeName(n);
std.debug.print("{d}->{d}\n", .{node.id, n.id});
printGraph(n);
}
}
pub fn main() !void {
var gpa = std.heap.DebugAllocator(.{}).init;
defer {
//_ = gpa.detectLeaks();
}
const allocator = gpa.allocator();
var lexer = al.Lexer.init(@constCast("3*2+2.2"));
var parser = al.Parser.init(allocator, &lexer);
defer parser.deinit();
const graph = try parser.buildGraph();
defer graph.?.deinit(&parser);
std.debug.print("digraph G {{\n", .{});
nodeName(graph.?);
printGraph(graph.?);
std.debug.print("}}\n", .{});
}

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pub const Lexer = @import("Lexer.zig");
pub const Parser = @import("Parser.zig");