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cex: always show ε/%empty in counterexamples
On a case such as
%%
exp
: empty "a"
| "a" empty
empty
: %empty
we used to display
warning: shift/reduce conflict on token "a" [-Wcounterexamples]
Example: • "a"
Shift derivation
exp
↳ 2: • "a" empty
↳ 2: ε
Example: • "a"
Reduce derivation
exp
↳ 1: empty "a"
↳ 3: •
where the shift derivation shows an item "2: empty → ε", with an
explicit "ε", but the reduce derivation shows "3: empty → •", without
"ε".
For consistency, let's always show ε/%empty in rules with an empty
rhs:
Reduce derivation
exp
↳ 1: empty "a"
↳ 3: ε •
* src/derivation.c (derivation_width, derivation_print_tree_impl):
Always show ε/%empty in counterexamples.
* tests/diagnostics.at: Check that case.
* tests/conflicts.at, tests/counterexample.at: Adjust.
This commit is contained in:
Akim Demaille
11
NEWS
11
NEWS
@@ -19,17 +19,18 @@ GNU Bison NEWS
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*** Counterexamples
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Counterexamples now show the rule numbers:
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Counterexamples now show the rule numbers, and always show ε for rules
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with an empty right-hand side. For instance
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exp
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↳ 1: "if" exp "then" exp
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↳ 2: "if" exp "then" exp • "else" exp
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↳ 1: e1 e2 "a"
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↳ 3: ε • ↳ 1: ε
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instead of
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exp
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↳ "if" exp "then" exp
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↳ "if" exp "then" exp • "else" exp
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↳ e1 e2 "a"
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↳ • ↳ ε
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* Noteworthy changes in release 3.7.1 (2020-08-02) [stable]
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@@ -10605,8 +10605,8 @@ This shows two separate derivations in the grammar for the same @code{exp}:
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given example. Here, the first derivation completes a reduction when seeing
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@samp{/}, causing @samp{e1 + e2} to be grouped as an @code{exp}. The second
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derivation shifts on @samp{/}, resulting in @samp{e2 / e3} being grouped as
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an @code{exp}. Therefore, it is easy to see that adding @code{%precedence}
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directives would fix this conflict.
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an @code{exp}. Therefore, it is easy to see that adding
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precedence/associativity directives would fix this conflict.
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The remaining states are similar:
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@@ -245,6 +245,13 @@ derivation_width (const derivation *deriv)
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children_width += empty_width;
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else
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{
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if (gl_list_size (deriv->children) == 1
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&& gl_list_get_first (deriv->children) == &d_dot)
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{
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children_width += empty_width;
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children_width += derivation_separator_width;
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}
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derivation *child;
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for (gl_list_iterator_t it = gl_list_iterator (deriv->children);
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derivation_list_next (&it, &child);
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@@ -310,6 +317,13 @@ derivation_print_tree_impl (const derivation *deriv, FILE *out,
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res += fputs_if (depth == 1, out, padding, empty);
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else
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{
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if (gl_list_size (deriv->children) == 1
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&& gl_list_get_first (deriv->children) == &d_dot)
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{
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res += fputs_if (depth == 1, out, padding, empty);
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res += fputs_if (depth == 1, out, padding, derivation_separator);
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}
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bool first = true;
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derivation *child;
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for (gl_list_iterator_t it = gl_list_iterator (deriv->children);
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@@ -1776,7 +1776,7 @@ State 4
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Reduce derivation
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start
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`-> 1: resolved_conflict reported_conflicts 'a'
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`-> 10: .
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`-> 10: %empty .
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shift/reduce conflict on token 'a':
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10 reported_conflicts: . %empty
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@@ -1790,7 +1790,7 @@ State 4
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Reduce derivation
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start
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`-> 1: resolved_conflict reported_conflicts 'a'
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`-> 10: .
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`-> 10: %empty .
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@@ -1999,12 +1999,12 @@ AT_CHECK([[cat input.output | sed -n '/^State 0$/,/^State 1$/p']], 0,
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Example: . 'c'
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First reduce derivation
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start
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`-> 7: empty_c2 'c'
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`-> 12: .
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`-> 7: empty_c2 'c'
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`-> 12: %empty .
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Second reduce derivation
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start
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`-> 8: empty_c3 'c'
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`-> 13: .
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`-> 8: empty_c3 'c'
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`-> 13: %empty .
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@@ -164,9 +164,9 @@ input.y: warning: shift/reduce conflict on token B [-Wcounterexamples]
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`-> 9: . B
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Reduce derivation
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s
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`-> 1: ax by
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`-> 3: A x `-> 6: B y
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`-> 4: . `-> 6: %empty
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`-> 1: ax by
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`-> 3: A x `-> 6: B y
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`-> 4: %empty . `-> 6: %empty
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input.y: warning: shift/reduce conflict on token B [-Wcounterexamples]
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First example: A X . B Y $end
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Shift derivation
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@@ -178,11 +178,11 @@ input.y: warning: shift/reduce conflict on token B [-Wcounterexamples]
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Second example: A X . B y $end
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Reduce derivation
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$accept
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`-> 0: s $end
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`-> 1: ax by
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`-> 3: A x `-> 6: B y
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`-> 0: s $end
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`-> 1: ax by
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`-> 3: A x `-> 6: B y
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`-> 5: X x
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`-> 4: .
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`-> 4: %empty .
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input.y:5.4-9: warning: rule useless in parser due to conflicts [-Wother]
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]],
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[[input.y: warning: 2 shift/reduce conflicts [-Wconflicts-sr]
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@@ -571,10 +571,10 @@ input.y: warning: reduce/reduce conflict on tokens b, c [-Wcounterexamples]
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Second reduce derivation
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S
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`-> 1: B C
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`-> 7: A c A
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`-> 3: B `-> 7: %empty
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`-> 6: A b A
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`-> 5: . `-> 6: %empty
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`-> 7: A c A
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`-> 3: B `-> 7: %empty
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`-> 6: A b A
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`-> 5: %empty . `-> 6: %empty
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input.y: warning: reduce/reduce conflict on tokens b, c [-Wcounterexamples]
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Example: C . c b
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First reduce derivation
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@@ -585,10 +585,10 @@ input.y: warning: reduce/reduce conflict on tokens b, c [-Wcounterexamples]
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Second reduce derivation
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S
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`-> 2: C B
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`-> 6: A b A
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`-> 4: C `-> 6: %empty
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`-> 7: A c A
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`-> 5: . `-> 7: %empty
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`-> 6: A b A
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`-> 4: C `-> 6: %empty
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`-> 7: A c A
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`-> 5: %empty . `-> 7: %empty
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]],
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[[input.y: warning: 4 reduce/reduce conflicts [-Wconflicts-rr]
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input.y: warning: reduce/reduce conflict on tokens b, c [-Wcounterexamples]
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@@ -625,49 +625,49 @@ input.y: warning: reduce/reduce conflict on token A [-Wcounterexamples]
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First example: . c A A $end
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First reduce derivation
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$accept
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`-> 0: a $end
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`-> 1: b d
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`-> 3: . `-> 6: c A A
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`-> 0: a $end
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`-> 1: b d
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`-> 3: %empty . `-> 6: c A A
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Second example: . c A A $end
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Second reduce derivation
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$accept
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`-> 0: a $end
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`-> 2: c d
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`-> 4: . `-> 6: c A A
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`-> 0: a $end
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`-> 2: c d
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`-> 4: %empty . `-> 6: c A A
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input.y: warning: reduce/reduce conflict on token A [-Wcounterexamples]
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time limit exceeded: XXX
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First example: b . c A A $end
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First reduce derivation
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$accept
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`-> 0: a $end
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`-> 0: a $end
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`-> 1: b d
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`-> 5: a
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`-> 1: b d
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`-> 3: . `-> 6: c A A
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`-> 1: b d
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`-> 3: %empty . `-> 6: c A A
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Second example: b . A $end
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Second reduce derivation
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$accept
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`-> 0: a $end
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`-> 0: a $end
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`-> 1: b d
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`-> 6: c A
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`-> 4: .
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`-> 6: c A
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`-> 4: %empty .
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input.y: warning: reduce/reduce conflict on token A [-Wcounterexamples]
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time limit exceeded: XXX
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First example: c . c A A $end
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First reduce derivation
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$accept
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`-> 0: a $end
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`-> 0: a $end
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`-> 2: c d
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`-> 5: a
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`-> 1: b d
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`-> 3: . `-> 6: c A A
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`-> 1: b d
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`-> 3: %empty . `-> 6: c A A
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Second example: c . A $end
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Second reduce derivation
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$accept
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`-> 0: a $end
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`-> 0: a $end
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`-> 2: c d
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`-> 6: c A
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`-> 4: .
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`-> 6: c A
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`-> 4: %empty .
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input.y: warning: shift/reduce conflict on token A [-Wcounterexamples]
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time limit exceeded: XXX
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First example: b c . A
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@@ -678,33 +678,33 @@ time limit exceeded: XXX
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Second example: b c . c A A $end
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Reduce derivation
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$accept
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`-> 0: a $end
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`-> 0: a $end
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`-> 1: b d
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`-> 5: a
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`-> 2: c d
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`-> 5: a
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`-> 1: b d
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`-> 3: . `-> 6: c A A
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`-> 1: b d
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`-> 3: %empty . `-> 6: c A A
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input.y: warning: reduce/reduce conflict on token A [-Wcounterexamples]
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First example: b c . c A A $end
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First reduce derivation
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$accept
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`-> 0: a $end
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`-> 0: a $end
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`-> 1: b d
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`-> 5: a
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`-> 2: c d
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`-> 5: a
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`-> 1: b d
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`-> 3: . `-> 6: c A A
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`-> 1: b d
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`-> 3: %empty . `-> 6: c A A
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Second example: b c . A $end
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Second reduce derivation
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$accept
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`-> 0: a $end
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`-> 0: a $end
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`-> 1: b d
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`-> 5: a
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`-> 2: c d
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`-> 6: c A
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`-> 4: .
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`-> 6: c A
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`-> 4: %empty .
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input.y: warning: shift/reduce conflict on token A [-Wcounterexamples]
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First example: b c . A
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Shift derivation
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@@ -714,12 +714,12 @@ input.y: warning: shift/reduce conflict on token A [-Wcounterexamples]
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Second example: b c . A $end
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Reduce derivation
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$accept
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`-> 0: a $end
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`-> 0: a $end
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`-> 1: b d
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`-> 5: a
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`-> 2: c d
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`-> 6: c A
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`-> 4: .
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`-> 6: c A
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`-> 4: %empty .
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input.y: warning: reduce/reduce conflict on token $end [-Wcounterexamples]
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Example: b d .
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First reduce derivation
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@@ -861,10 +861,10 @@ input.y: warning: shift/reduce conflict on token D [-Wcounterexamples]
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`-> 6: . D
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Reduce derivation
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s
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`-> 2: A a a d
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`-> 3: b `-> 6: D
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`-> 2: A a a d
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`-> 3: b `-> 6: D
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`-> 4: c
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`-> 5: .
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`-> 5: %empty .
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]],
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[[input.y: warning: 1 shift/reduce conflict [-Wconflicts-sr]
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input.y: warning: shift/reduce conflict on token D [-Wcounterexamples]
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@@ -905,11 +905,11 @@ input.y: warning: shift/reduce conflict on token D [-Wcounterexamples]
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Second example: A a . D E $end
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Reduce derivation
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$accept
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`-> 0: s $end
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`-> 2: A a a d E
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`-> 3: b `-> 6: D
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`-> 0: s $end
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`-> 2: A a a d E
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`-> 3: b `-> 6: D
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`-> 4: c
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`-> 5: .
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`-> 5: %empty .
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]],
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[[input.y: warning: 1 shift/reduce conflict [-Wconflicts-sr]
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input.y: warning: shift/reduce conflict on token D [-Wcounterexamples]
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@@ -532,9 +532,58 @@ exp
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exp
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: "if" exp "then" exp
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| "if" exp "then" exp "else" exp
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| exp "+" exp
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| "num"
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| empty "a"
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| "a" empty
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|
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empty
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: %empty
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]],
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]],
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[1],
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[[input.y: <error>error:</error> shift/reduce conflicts: 9 found, 0 expected
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input.y: <warning>warning:</warning> shift/reduce conflict on token "a" [<warning>-Wcounterexamples</warning>]
|
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Example: <cex-0><cex-dot>•</cex-dot> <cex-leaf>"a"</cex-leaf><cex-1></cex-1></cex-0>
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Shift derivation
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<cex-0><cex-step>exp</cex-step></cex-0>
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<cex-0><cex-step>↳ 6: <cex-dot>•</cex-dot><cex-leaf> "a"</cex-leaf><cex-1><cex-step> empty</cex-step></cex-1></cex-step></cex-0>
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<cex-1><cex-step> ↳ 6: ε</cex-step></cex-1>
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Example: <cex-0><cex-1><cex-dot>•</cex-dot></cex-1> <cex-leaf>"a"</cex-leaf></cex-0>
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Reduce derivation
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<cex-0><cex-step>exp</cex-step></cex-0>
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<cex-0><cex-step>↳ 5: <cex-1><cex-step>empty</cex-step></cex-1><cex-leaf> "a"</cex-leaf></cex-step></cex-0>
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<cex-1><cex-step> ↳ 7: ε<cex-dot> •</cex-dot></cex-step></cex-1>
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input.y: <warning>warning:</warning> shift/reduce conflict on token "a" [<warning>-Wcounterexamples</warning>]
|
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Example: <cex-0><cex-dot>•</cex-dot> <cex-leaf>"a"</cex-leaf><cex-1></cex-1></cex-0>
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Shift derivation
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<cex-0><cex-step>exp</cex-step></cex-0>
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<cex-0><cex-step>↳ 6: <cex-dot>•</cex-dot><cex-leaf> "a"</cex-leaf><cex-1><cex-step> empty</cex-step></cex-1></cex-step></cex-0>
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<cex-1><cex-step> ↳ 6: ε</cex-step></cex-1>
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Example: <cex-0><cex-1><cex-dot>•</cex-dot></cex-1> <cex-leaf>"a"</cex-leaf></cex-0>
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Reduce derivation
|
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<cex-0><cex-step>exp</cex-step></cex-0>
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<cex-0><cex-step>↳ 5: <cex-1><cex-step>empty</cex-step></cex-1><cex-leaf> "a"</cex-leaf></cex-step></cex-0>
|
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<cex-1><cex-step> ↳ 7: ε<cex-dot> •</cex-dot></cex-step></cex-1>
|
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input.y: <warning>warning:</warning> shift/reduce conflict on token "a" [<warning>-Wcounterexamples</warning>]
|
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Example: <cex-0><cex-dot>•</cex-dot> <cex-leaf>"a"</cex-leaf><cex-1></cex-1></cex-0>
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Shift derivation
|
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<cex-0><cex-step>exp</cex-step></cex-0>
|
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<cex-0><cex-step>↳ 6: <cex-dot>•</cex-dot><cex-leaf> "a"</cex-leaf><cex-1><cex-step> empty</cex-step></cex-1></cex-step></cex-0>
|
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<cex-1><cex-step> ↳ 6: ε</cex-step></cex-1>
|
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Example: <cex-0><cex-1><cex-dot>•</cex-dot></cex-1> <cex-leaf>"a"</cex-leaf></cex-0>
|
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Reduce derivation
|
||||
<cex-0><cex-step>exp</cex-step></cex-0>
|
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<cex-0><cex-step>↳ 5: <cex-1><cex-step>empty</cex-step></cex-1><cex-leaf> "a"</cex-leaf></cex-step></cex-0>
|
||||
<cex-1><cex-step> ↳ 7: ε<cex-dot> •</cex-dot></cex-step></cex-1>
|
||||
input.y: <warning>warning:</warning> shift/reduce conflict on token "a" [<warning>-Wcounterexamples</warning>]
|
||||
Example: <cex-0><cex-dot>•</cex-dot> <cex-leaf>"a"</cex-leaf><cex-1></cex-1></cex-0>
|
||||
Shift derivation
|
||||
<cex-0><cex-step>exp</cex-step></cex-0>
|
||||
<cex-0><cex-step>↳ 6: <cex-dot>•</cex-dot><cex-leaf> "a"</cex-leaf><cex-1><cex-step> empty</cex-step></cex-1></cex-step></cex-0>
|
||||
<cex-1><cex-step> ↳ 6: ε</cex-step></cex-1>
|
||||
Example: <cex-0><cex-1><cex-dot>•</cex-dot></cex-1> <cex-leaf>"a"</cex-leaf></cex-0>
|
||||
Reduce derivation
|
||||
<cex-0><cex-step>exp</cex-step></cex-0>
|
||||
<cex-0><cex-step>↳ 5: <cex-1><cex-step>empty</cex-step></cex-1><cex-leaf> "a"</cex-leaf></cex-step></cex-0>
|
||||
<cex-1><cex-step> ↳ 7: ε<cex-dot> •</cex-dot></cex-step></cex-1>
|
||||
input.y: <warning>warning:</warning> shift/reduce conflict on token "+" [<warning>-Wcounterexamples</warning>]
|
||||
@@ -568,6 +617,17 @@ input.y: <warning>warning:</warning> shift/reduce conflict on token "+" [<warnin
|
||||
Example: <cex-0><cex-1><cex-leaf>"if"</cex-leaf> <cex-leaf>exp</cex-leaf> <cex-leaf>"then"</cex-leaf> <cex-leaf>exp</cex-leaf> <cex-dot>•</cex-dot></cex-1> <cex-leaf>"+"</cex-leaf> <cex-leaf>exp</cex-leaf></cex-0>
|
||||
Reduce derivation
|
||||
<cex-0><cex-step>exp</cex-step></cex-0>
|
||||
<cex-0><cex-step>↳ 3: <cex-1><cex-step>exp</cex-step></cex-1><cex-leaf> "+"</cex-leaf><cex-leaf> exp</cex-leaf></cex-step></cex-0>
|
||||
<cex-1><cex-step> ↳ 1: <cex-leaf>"if"</cex-leaf><cex-leaf> exp</cex-leaf><cex-leaf> "then"</cex-leaf><cex-leaf> exp</cex-leaf><cex-dot> •</cex-dot></cex-step></cex-1>
|
||||
input.y: <warning>warning:</warning> shift/reduce conflict on token "a" [<warning>-Wcounterexamples</warning>]
|
||||
Example: <cex-0><cex-dot>•</cex-dot> <cex-leaf>"a"</cex-leaf><cex-1></cex-1></cex-0>
|
||||
Shift derivation
|
||||
<cex-0><cex-step>exp</cex-step></cex-0>
|
||||
<cex-0><cex-step>↳ 6: <cex-dot>•</cex-dot><cex-leaf> "a"</cex-leaf><cex-1><cex-step> empty</cex-step></cex-1></cex-step></cex-0>
|
||||
<cex-1><cex-step> ↳ 6: ε</cex-step></cex-1>
|
||||
Example: <cex-0><cex-1><cex-dot>•</cex-dot></cex-1> <cex-leaf>"a"</cex-leaf></cex-0>
|
||||
Reduce derivation
|
||||
<cex-0><cex-step>exp</cex-step></cex-0>
|
||||
<cex-0><cex-step>↳ 5: <cex-1><cex-step>empty</cex-step></cex-1><cex-leaf> "a"</cex-leaf></cex-step></cex-0>
|
||||
<cex-1><cex-step> ↳ 7: ε<cex-dot> •</cex-dot></cex-step></cex-1>
|
||||
input.y: <warning>warning:</warning> shift/reduce conflict on token "+" [<warning>-Wcounterexamples</warning>]
|
||||
|
||||
Reference in New Issue
Block a user