226 lines
5.8 KiB
C++
226 lines
5.8 KiB
C++
//: For convenience, some instructions will take literal arrays of characters
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//: (text or strings).
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//:
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//: Instead of quotes, we'll use [] to delimit strings. That'll reduce the
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//: need for escaping since we can support nested brackets. And we can also
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//: imagine that 'recipe' might one day itself be defined in Mu, doing its own
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//: parsing.
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:(scenarios load)
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:(scenario string_literal)
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def main [
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1:address:array:character <- copy [abc def]
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]
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+parse: ingredient: {"abc def": "literal-string"}
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:(scenario string_literal_with_colons)
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def main [
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1:address:array:character <- copy [abc:def/ghi]
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]
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+parse: ingredient: {"abc:def/ghi": "literal-string"}
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:(before "End Mu Types Initialization")
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put(Type_ordinal, "literal-string", 0);
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:(before "End next_word Special-cases")
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if (in.peek() == '[') {
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string result = slurp_quoted(in);
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skip_whitespace_and_comments_but_not_newline(in);
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return result;
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}
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:(code)
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string slurp_quoted(istream& in) {
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ostringstream out;
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assert(has_data(in)); assert(in.peek() == '['); out << static_cast<char>(in.get()); // slurp the '['
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if (is_code_string(in, out))
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slurp_quoted_comment_aware(in, out);
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else
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slurp_quoted_comment_oblivious(in, out);
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return out.str();
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}
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// A string is a code string (ignores comments when scanning for matching
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// brackets) if it contains a newline at the start before any non-whitespace.
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bool is_code_string(istream& in, ostream& out) {
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while (has_data(in)) {
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char c = in.get();
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if (!isspace(c)) {
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in.putback(c);
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return false;
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}
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out << c;
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if (c == '\n') {
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return true;
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}
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}
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return false;
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}
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// Read a regular string. Regular strings can only contain other regular
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// strings.
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void slurp_quoted_comment_oblivious(istream& in, ostream& out) {
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int brace_depth = 1;
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while (has_data(in)) {
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char c = in.get();
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if (c == '\\') {
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slurp_one_past_backslashes(in, out);
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continue;
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}
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out << c;
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if (c == '[') ++brace_depth;
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if (c == ']') --brace_depth;
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if (brace_depth == 0) break;
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}
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if (!has_data(in) && brace_depth > 0) {
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raise << "unbalanced '['\n" << end();
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out.clear();
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}
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}
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// Read a code string. Code strings can contain either code or regular strings.
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void slurp_quoted_comment_aware(istream& in, ostream& out) {
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char c;
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while (in >> c) {
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if (c == '\\') {
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slurp_one_past_backslashes(in, out);
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continue;
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}
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if (c == '#') {
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out << c;
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while (has_data(in) && in.peek() != '\n') out << static_cast<char>(in.get());
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continue;
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}
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if (c == '[') {
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in.putback(c);
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// recurse
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out << slurp_quoted(in);
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continue;
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}
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out << c;
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if (c == ']') return;
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}
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raise << "unbalanced '['\n" << end();
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out.clear();
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}
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:(after "Parsing reagent(string s)")
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if (starts_with(s, "[")) {
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if (*s.rbegin() != ']') return; // unbalanced bracket; handled elsewhere
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name = s;
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// delete [] delimiters
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name.erase(0, 1);
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strip_last(name);
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type = new type_tree("literal-string", 0);
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return;
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}
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//: Unlike other reagents, escape newlines in literal strings to make them
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//: more friendly to trace().
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:(after "string to_string(const reagent& r)")
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if (is_literal_text(r))
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return emit_literal_string(r.name);
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:(code)
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bool is_literal_text(const reagent& x) {
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return x.type && x.type->name == "literal-string";
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}
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string emit_literal_string(string name) {
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size_t pos = 0;
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while (pos != string::npos)
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pos = replace(name, "\n", "\\n", pos);
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return "{\""+name+"\": \"literal-string\"}";
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}
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size_t replace(string& str, const string& from, const string& to, size_t n) {
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size_t result = str.find(from, n);
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if (result != string::npos)
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str.replace(result, from.length(), to);
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return result;
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}
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void strip_last(string& s) {
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if (!s.empty()) s.erase(SIZE(s)-1);
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}
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void slurp_one_past_backslashes(istream& in, ostream& out) {
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// When you encounter a backslash, strip it out and pass through any
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// following run of backslashes. If we 'escaped' a single following
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// character, then the character '\' would be:
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// '\\' escaped once
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// '\\\\' escaped twice
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// '\\\\\\\\' escaped thrice (8 backslashes)
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// ..and so on. With our approach it'll be:
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// '\\' escaped once
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// '\\\' escaped twice
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// '\\\\' escaped thrice
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// This only works as long as backslashes aren't also overloaded to create
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// special characters. So Mu doesn't follow C's approach of overloading
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// backslashes both to escape quote characters and also as a notation for
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// unprintable characters like '\n'.
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while (has_data(in)) {
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char c = in.get();
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out << c;
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if (c != '\\') break;
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}
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}
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:(scenario string_literal_nested)
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def main [
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1:address:array:character <- copy [abc [def]]
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]
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+parse: ingredient: {"abc [def]": "literal-string"}
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:(scenario string_literal_escaped)
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def main [
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1:address:array:character <- copy [abc \[def]
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]
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+parse: ingredient: {"abc [def": "literal-string"}
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:(scenario string_literal_escaped_twice)
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def main [
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1:address:array:character <- copy [
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abc \\[def]
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]
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+parse: ingredient: {"\nabc \[def": "literal-string"}
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:(scenario string_literal_and_comment)
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def main [
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1:address:array:character <- copy [abc] # comment
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]
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+parse: --- defining main
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+parse: instruction: copy
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+parse: number of ingredients: 1
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+parse: ingredient: {"abc": "literal-string"}
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+parse: product: {1: ("address" "array" "character")}
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:(scenario string_literal_escapes_newlines_in_trace)
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def main [
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copy [abc
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def]
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]
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+parse: ingredient: {"abc\ndef": "literal-string"}
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:(scenario string_literal_can_skip_past_comments)
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def main [
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copy [
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# ']' inside comment
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bar
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]
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]
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+parse: ingredient: {"\n # ']' inside comment\n bar\n ": "literal-string"}
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:(scenario string_literal_empty)
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def main [
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copy []
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]
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+parse: ingredient: {"": "literal-string"}
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:(scenario multiple_unfinished_recipes)
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% Hide_errors = true;
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def f1 [
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def f2 [
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+error: unbalanced '['
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