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internal/calc gets its own tokenizer and precedence-climbing parser in place of go/parser, which cannot express a power operator; go/constant still computes. ^ (also **) binds tighter than * / % and a sign on its left, and groups to the right. % takes the sign of the divisor and is exact on decimals. A whole exponent is computed exactly while the result's numerator and denominator stay within 4096 bits; otherwise, and for a fractional exponent, in float64. A remainder, or the sign of a negative base's power, that depends on a value go/constant holds rounded is refused as too large. The welcome text and the replies mention the new operators; a negative base with a fractional exponent gets its own reply. Model: opus-5-5
292 lines
9.0 KiB
Go
292 lines
9.0 KiB
Go
package calc_test
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import (
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"errors"
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"strings"
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"testing"
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"time"
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"sneak.berlin/go/simplexcalc/internal/calc"
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)
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// TestEvaluate covers the two examples the bot was specified with, and
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// the arithmetic around them.
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func TestEvaluate(t *testing.T) {
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t.Parallel()
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expectResults(t, map[string]string{
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// The specification's own examples.
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"2 + 2": "4",
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"5 * 5/2": "12.5",
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"2+2": "4",
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" 7 - 10 \n": "-3",
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"-3 * 2": "-6",
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"+4": "4",
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"-(-4)": "4",
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"(1 + 2) * 3": "9",
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"1 + 2 * 3": "7",
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"((2))": "2",
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"8 / 2 / 2": "2",
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"10 - 2 - 3": "5",
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"7 / 2": "3.5",
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"25/2": "12.5",
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"1 / 3": "0.3333333333333333",
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"2 / 3": "0.6666666666666666",
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"0.1 + 0.2": "0.3",
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"1.5 * 2": "3",
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"2.50 * 2": "5",
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".5 + .5": "1",
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"3. * 2": "6",
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"1e3 + 1": "1001",
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"2.5e-1": "0.25",
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"010 + 1": "11",
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"-0": "0",
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"0 / 5": "0",
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// Exact: a float64 would print 99999999980000000000.
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"9999999999 * 9999999999": "99999999980000000001",
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"1e21": "1e+21",
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"1e20": "100000000000000000000",
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"1 / 1e7": "1e-07",
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"1 / 1e6": "0.000001",
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"1234567.5": "1234567.5",
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"-1 / 4": "-0.25",
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"1e300 * 1e8": "1e+308",
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})
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}
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// TestEvaluatePowers: ^ and ** are one operator, binding tighter than
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// * / % and a sign on its left, and grouping to the right.
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func TestEvaluatePowers(t *testing.T) {
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t.Parallel()
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expectResults(t, map[string]string{
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"2^3": "8",
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"2**3": "8",
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"2 ** 3 ^ 2": "512",
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"2^3^2": "512",
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"(2^3)^2": "64",
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"-2^2": "-4",
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"(-2)^2": "4",
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"(-2)^3": "-8",
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"(-2)^-3": "-0.125",
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"2^-1": "0.5",
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"2**-1": "0.5",
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"-2^-2": "-0.25",
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"2^-3^2": "0.001953125",
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"2 * 3^2": "18",
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"3^2 * 2": "18",
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"2^3 / 2^2": "2",
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"1 + 2^3 - 3^2": "0",
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"010^2": "100",
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"0.1^2": "0.01",
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"2^100 - 2^100 + 1": "1",
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"2^64": "18446744073709551616",
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"0^0": "1",
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"0^3": "0",
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"1.5^2": "2.25",
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"2^0.5": "1.4142135623730951",
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"-2^0.5": "-1.4142135623730951",
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"4^0.5": "2",
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"0^0.5": "0",
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"2^1023": "8.98846567431158e+307",
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// Past 2^53 a float64 cannot tell odd from even.
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"(-1)^(2^53 + 1)": "-1",
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"(-1)^(10^30)": "1",
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})
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}
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// TestEvaluateModulo: % sits with * and /, left to right, and its result
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// takes the sign of the divisor.
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func TestEvaluateModulo(t *testing.T) {
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t.Parallel()
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expectResults(t, map[string]string{
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"7 % 3": "1",
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"-7 % 3": "2",
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"7 % -3": "-2",
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"-7 % -3": "-1",
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"6 % 3": "0",
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"-6 % 3": "0",
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"7.5 % 2": "1.5",
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"0.3 % 0.1": "0",
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"-0.3 % 0.2": "0.1",
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"10 % 4 * 3": "6",
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"2 * 7 % 4": "2",
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"1 + 7 % 3": "2",
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"2^10 % 7": "2",
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"10^400 % 7": "4",
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"1e-30 % 1": "1e-30",
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"-1e-30 % 1": "1",
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"10 / 8 % 1": "0.25",
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"(7 % 3)^2": "1",
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"7 % (3 ^ 2)": "7",
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})
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}
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// expectResults checks that each expression evaluates to its result.
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func expectResults(t *testing.T, cases map[string]string) {
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t.Helper()
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for in, want := range cases {
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t.Run(in, func(t *testing.T) {
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t.Parallel()
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got, err := calc.Evaluate(in)
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if err != nil {
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t.Fatalf("Evaluate(%q) failed: %v", in, err)
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}
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if got != want {
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t.Errorf("Evaluate(%q) = %q, want %q", in, got, want)
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}
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})
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}
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}
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// TestEvaluateRefuses covers what must be answered with an error rather
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// than a number, and never with a panic.
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func TestEvaluateRefuses(t *testing.T) {
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t.Parallel()
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cases := map[string]error{
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"": calc.ErrNotArithmetic,
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" ": calc.ErrNotArithmetic,
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"hello": calc.ErrNotArithmetic,
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"/help": calc.ErrNotArithmetic,
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"2 +": calc.ErrNotArithmetic,
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"2 2": calc.ErrNotArithmetic,
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"2 + 2 =": calc.ErrNotArithmetic,
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"x + 1": calc.ErrNotArithmetic,
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"len(\"abc\")": calc.ErrNotArithmetic,
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"\"a\" + \"b\"": calc.ErrNotArithmetic,
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"'a' + 1": calc.ErrNotArithmetic,
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"2i * 2i": calc.ErrNotArithmetic,
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"0x10 + 1": calc.ErrNotArithmetic,
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"1_000 + 1": calc.ErrNotArithmetic,
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"1 << 10": calc.ErrNotArithmetic,
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"1 == 1": calc.ErrNotArithmetic,
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"!1": calc.ErrNotArithmetic,
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"func() int { return 1 }()": calc.ErrNotArithmetic,
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"(1 + 2": calc.ErrNotArithmetic,
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"1 + 2)": calc.ErrNotArithmetic,
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"()": calc.ErrNotArithmetic,
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"(2)(3)": calc.ErrNotArithmetic,
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"2 ^": calc.ErrNotArithmetic,
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"^ 2": calc.ErrNotArithmetic,
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"2 ^^ 3": calc.ErrNotArithmetic,
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"2 *** 3": calc.ErrNotArithmetic,
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"2 * * 3": calc.ErrNotArithmetic,
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"% 3": calc.ErrNotArithmetic,
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"50%": calc.ErrNotArithmetic,
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"2 × 3": calc.ErrNotArithmetic,
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"1 / 0": calc.ErrDivisionByZero,
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"1 / (2 - 2)": calc.ErrDivisionByZero,
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"5 / 0.0": calc.ErrDivisionByZero,
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"7 % 0": calc.ErrDivisionByZero,
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"7.5 % (1 - 1)": calc.ErrDivisionByZero,
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"0^-1": calc.ErrDivisionByZero,
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"0^-0.5": calc.ErrDivisionByZero,
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"(-2)^0.5": calc.ErrNoRealResult,
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"(-8)^(1/3)": calc.ErrNoRealResult,
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"(-1)^-0.5": calc.ErrNoRealResult,
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"1e400": calc.ErrTooLarge,
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"1e300 * 1e300": calc.ErrTooLarge,
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"1e999999999 * 1e999999999": calc.ErrTooLarge,
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"1 / 1e-400": calc.ErrTooLarge,
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"2^1024": calc.ErrTooLarge,
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"2^5000": calc.ErrTooLarge,
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"(-2)^5001": calc.ErrTooLarge,
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"0.5^-5000": calc.ErrTooLarge,
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// go/constant holds a product of this size rounded, so the
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// remainder, or the sign of -1 to its power, cannot be known.
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"7^1000 * 7^1000 / 7^1000 % 10": calc.ErrTooLarge,
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"(-1)^(3^1365 * 3^1365 / 3^1365)": calc.ErrTooLarge,
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"(-1)^1e1300": calc.ErrTooLarge,
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}
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for in, want := range cases {
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t.Run(in, func(t *testing.T) {
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t.Parallel()
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got, err := calc.Evaluate(in)
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if !errors.Is(err, want) {
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t.Errorf("Evaluate(%q) = %q, %v; want error %v", in, got, err, want)
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}
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})
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}
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}
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// TestEvaluateBoundsWork: computed exactly, each of these powers would
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// need more time and memory than any machine has. They must be answered
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// at once.
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func TestEvaluateBoundsWork(t *testing.T) {
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t.Parallel()
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cases := []struct {
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in string
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want string
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err error
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}{
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{in: "9^9^9^9^9", err: calc.ErrTooLarge},
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{in: "((9^999)^999)^999", err: calc.ErrTooLarge},
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{in: "1.0000001^99999", want: "1.01005006557947"},
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{in: "0.5^99999999999999999999", want: "0"},
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{in: "(-1)^99999999999999999999", want: "-1"},
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// The longest tower that fits.
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{in: strings.Repeat("9^", 127) + "9", err: calc.ErrTooLarge},
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// The largest power computed exactly, as often as fits.
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{in: strings.Repeat("3^1365*", 36) + "0", want: "0"},
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}
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for _, c := range cases {
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t.Run(c.in, func(t *testing.T) {
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t.Parallel()
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start := time.Now()
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got, err := calc.Evaluate(c.in)
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if elapsed := time.Since(start); elapsed > time.Second {
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t.Errorf("Evaluate(%q) took %v", c.in, elapsed)
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}
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if !errors.Is(err, c.err) || got != c.want {
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t.Errorf("Evaluate(%q) = %q, %v; want %q, %v", c.in, got, err, c.want, c.err)
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}
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})
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}
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}
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// TestEvaluateCapsInput: the length cap is what bounds the work a
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// message can cause, so it must hold exactly at the boundary.
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func TestEvaluateCapsInput(t *testing.T) {
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t.Parallel()
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// "1+1+...+1" with the last term padded to land exactly on the cap.
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longest := strings.Repeat("1+", calc.MaxInputLength/2-1) + "10"
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if len(longest) != calc.MaxInputLength {
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t.Fatalf("test setup: expression is %d bytes, want %d",
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len(longest), calc.MaxInputLength)
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}
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got, err := calc.Evaluate(longest)
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if err != nil {
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t.Fatalf("an expression of exactly MaxInputLength bytes was refused: %v", err)
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}
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if want := "137"; got != want {
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t.Errorf("Evaluate(longest) = %q, want %q", got, want)
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}
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_, err = calc.Evaluate(longest + "0")
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if !errors.Is(err, calc.ErrTooLong) {
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t.Errorf("an expression over MaxInputLength gave %v, want ErrTooLong", err)
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}
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// Surrounding whitespace is not part of the expression.
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_, err = calc.Evaluate(" " + longest + "\n")
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if err != nil {
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t.Errorf("whitespace around a maximal expression counted against the cap: %v", err)
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}
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}
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