[Core] Add getreuer's Autocorrect feature to core (#15699)

Co-authored-by: Albert Y <76888457+filterpaper@users.noreply.github.com>

1 files changed, 287 insertions, 0 deletions

diff --git a/quantum/process_keycode/process_autocorrect.c b/quantum/process_keycode/process_autocorrect.c
new file mode 100644
index 0000000000..abae5e7811
--- /dev/null
+++ b/quantum/process_keycode/process_autocorrect.c
@@ -0,0 +1,287 @@
+// Copyright 2021 Google LLC
+// Copyright 2021 @filterpaper
+// SPDX-License-Identifier: Apache-2.0
+// Original source: https://getreuer.info/posts/keyboards/autocorrection
+
+#include "process_autocorrect.h"
+#include <string.h>
+#include "keycode_config.h"
+
+#if __has_include("autocorrect_data.h")
+#    include "autocorrect_data.h"
+#else
+#    pragma message "Autocorrect is using the default library."
+#    include "autocorrect_data_default.h"
+#endif
+
+static uint8_t typo_buffer[AUTOCORRECT_MAX_LENGTH] = {KC_SPC};
+static uint8_t typo_buffer_size                    = 1;
+
+/**
+ * @brief function for querying the enabled state of autocorrect
+ *
+ * @return true if enabled
+ * @return false if disabled
+ */
+bool autocorrect_is_enabled(void) {
+    return keymap_config.autocorrect_enable;
+}
+
+/**
+ * @brief Enables autocorrect and saves state to eeprom
+ *
+ */
+void autocorrect_enable(void) {
+    keymap_config.autocorrect_enable = true;
+    eeconfig_update_keymap(keymap_config.raw);
+}
+
+/**
+ * @brief Disables autocorrect and saves state to eeprom
+ *
+ */
+void autocorrect_disable(void) {
+    keymap_config.autocorrect_enable = false;
+    typo_buffer_size                 = 0;
+    eeconfig_update_keymap(keymap_config.raw);
+}
+
+/**
+ * @brief Toggles autocorrect's status and save state to eeprom
+ *
+ */
+void autocorrect_toggle(void) {
+    keymap_config.autocorrect_enable = !keymap_config.autocorrect_enable;
+    typo_buffer_size                 = 0;
+    eeconfig_update_keymap(keymap_config.raw);
+}
+
+/**
+ * @brief handler for determining if autocorrect should process keypress
+ *
+ * @param keycode Keycode registered by matrix press, per keymap
+ * @param record keyrecord_t structure
+ * @param typo_buffer_size passed along to allow resetting of autocorrect buffer
+ * @param mods allow processing of mod status
+ * @return true Allow autocorection
+ * @return false Stop processing and escape from autocorrect.
+ */
+__attribute__((weak)) bool process_autocorrect_user(uint16_t *keycode, keyrecord_t *record, uint8_t *typo_buffer_size, uint8_t *mods) {
+    // See quantum_keycodes.h for reference on these matched ranges.
+    switch (*keycode) {
+        // Exclude these keycodes from processing.
+        case KC_LSFT:
+        case KC_RSFT:
+        case KC_CAPS:
+        case QK_TO ... QK_ONE_SHOT_LAYER_MAX:
+        case QK_LAYER_TAP_TOGGLE ... QK_LAYER_MOD_MAX:
+        case QK_ONE_SHOT_MOD ... QK_ONE_SHOT_MOD_MAX:
+            return false;
+
+        // Mask for base keycode from shifted keys.
+        case QK_LSFT ... QK_LSFT + 255:
+        case QK_RSFT ... QK_RSFT + 255:
+            if (*keycode >= QK_LSFT && *keycode <= (QK_LSFT + 255)) {
+                *mods |= MOD_LSFT;
+            } else {
+                *mods |= MOD_RSFT;
+            }
+            *keycode &= 0xFF; // Get the basic keycode.
+            return true;
+#ifndef NO_ACTION_TAPPING
+        // Exclude tap-hold keys when they are held down
+        // and mask for base keycode when they are tapped.
+        case QK_LAYER_TAP ... QK_LAYER_TAP_MAX:
+#    ifdef NO_ACTION_LAYER
+            // Exclude Layer Tap, if layers are disabled
+            // but action tapping is still enabled.
+            return false;
+#    endif
+        case QK_MOD_TAP ... QK_MOD_TAP_MAX:
+            // Exclude hold keycode
+            if (!record->tap.count) {
+                return false;
+            }
+            *keycode &= 0xFF;
+            break;
+#else
+        case QK_MOD_TAP ... QK_MOD_TAP_MAX:
+        case QK_LAYER_TAP ... QK_LAYER_TAP_MAX:
+            // Exclude if disabled
+            return false;
+#endif
+        // Exclude swap hands keys when they are held down
+        // and mask for base keycode when they are tapped.
+        case QK_SWAP_HANDS ... QK_SWAP_HANDS_MAX:
+#ifdef SWAP_HANDS_ENABLE
+            if (*keycode >= 0x56F0 || !record->tap.count) {
+                return false;
+            }
+            *keycode &= 0xFF;
+            break;
+#else
+            // Exclude if disabled
+            return false;
+#endif
+    }
+
+    // Disable autocorrect while a mod other than shift is active.
+    if ((*mods & ~MOD_MASK_SHIFT) != 0) {
+        *typo_buffer_size = 0;
+        return false;
+    }
+
+    return true;
+}
+
+/**
+ * @brief handling for when autocorrection has been triggered
+ *
+ * @param backspaces number of characters to remove
+ * @param str pointer to PROGMEM string to replace mistyped seletion with
+ * @return true apply correction
+ * @return false user handled replacement
+ */
+__attribute__((weak)) bool apply_autocorrect(uint8_t backspaces, const char *str) {
+    return true;
+}
+
+/**
+ * @brief Process handler for autocorrect feature
+ *
+ * @param keycode Keycode registered by matrix press, per keymap
+ * @param record keyrecord_t structure
+ * @return true Continue processing keycodes, and send to host
+ * @return false Stop processing keycodes, and don't send to host
+ */
+bool process_autocorrect(uint16_t keycode, keyrecord_t *record) {
+    uint8_t mods = get_mods();
+#ifndef NO_ACTION_ONESHOT
+    mods |= get_oneshot_mods();
+#endif
+
+    if ((keycode >= AUTOCORRECT_ON && keycode <= AUTOCORRECT_TOGGLE) && record->event.pressed) {
+        if (keycode == AUTOCORRECT_ON) {
+            autocorrect_enable();
+        } else if (keycode == AUTOCORRECT_OFF) {
+            autocorrect_disable();
+        } else if (keycode == AUTOCORRECT_TOGGLE) {
+            autocorrect_toggle();
+        } else {
+            return true;
+        }
+
+        return false;
+    }
+
+    if (!keymap_config.autocorrect_enable) {
+        typo_buffer_size = 0;
+        return true;
+    }
+
+    if (!record->event.pressed) {
+        return true;
+    }
+
+    // autocorrect keycode verification and extraction
+    if (!process_autocorrect_user(&keycode, record, &typo_buffer_size, &mods)) {
+        return true;
+    }
+
+    // keycode buffer check
+    switch (keycode) {
+        case KC_A ... KC_Z:
+            // process normally
+            break;
+        case KC_1 ... KC_0:
+        case KC_TAB ... KC_SEMICOLON:
+        case KC_GRAVE ... KC_SLASH:
+            // Set a word boundary if space, period, digit, etc. is pressed.
+            keycode = KC_SPC;
+            break;
+        case KC_ENTER:
+            // Behave more conservatively for the enter key. Reset, so that enter
+            // can't be used on a word ending.
+            typo_buffer_size = 0;
+            keycode          = KC_SPC;
+            break;
+        case KC_BSPC:
+            // Remove last character from the buffer.
+            if (typo_buffer_size > 0) {
+                --typo_buffer_size;
+            }
+            return true;
+        case KC_QUOTE:
+            // Treat " (shifted ') as a word boundary.
+            if ((mods & MOD_MASK_SHIFT) != 0) {
+                keycode = KC_SPC;
+            }
+            break;
+        default:
+            // Clear state if some other non-alpha key is pressed.
+            typo_buffer_size = 0;
+            return true;
+    }
+
+    // Rotate oldest character if buffer is full.
+    if (typo_buffer_size >= AUTOCORRECT_MAX_LENGTH) {
+        memmove(typo_buffer, typo_buffer + 1, AUTOCORRECT_MAX_LENGTH - 1);
+        typo_buffer_size = AUTOCORRECT_MAX_LENGTH - 1;
+    }
+
+    // Append `keycode` to buffer.
+    typo_buffer[typo_buffer_size++] = keycode;
+    // Return if buffer is smaller than the shortest word.
+    if (typo_buffer_size < AUTOCORRECT_MIN_LENGTH) {
+        return true;
+    }
+
+    // Check for typo in buffer using a trie stored in `autocorrect_data`.
+    uint16_t state = 0;
+    uint8_t  code  = pgm_read_byte(autocorrect_data + state);
+    for (int8_t i = typo_buffer_size - 1; i >= 0; --i) {
+        uint8_t const key_i = typo_buffer[i];
+
+        if (code & 64) { // Check for match in node with multiple children.
+            code &= 63;
+            for (; code != key_i; code = pgm_read_byte(autocorrect_data + (state += 3))) {
+                if (!code) return true;
+            }
+            // Follow link to child node.
+            state = (pgm_read_byte(autocorrect_data + state + 1) | pgm_read_byte(autocorrect_data + state + 2) << 8);
+            // Check for match in node with single child.
+        } else if (code != key_i) {
+            return true;
+        } else if (!(code = pgm_read_byte(autocorrect_data + (++state)))) {
+            ++state;
+        }
+
+        // Stop if `state` becomes an invalid index. This should not normally
+        // happen, it is a safeguard in case of a bug, data corruption, etc.
+        if (state >= DICTIONARY_SIZE) {
+            return true;
+        }
+
+        code = pgm_read_byte(autocorrect_data + state);
+
+        if (code & 128) { // A typo was found! Apply autocorrect.
+            const uint8_t backspaces = (code & 63) + !record->event.pressed;
+            if (apply_autocorrect(backspaces, (char const *)(autocorrect_data + state + 1))) {
+                for (uint8_t i = 0; i < backspaces; ++i) {
+                    tap_code(KC_BSPC);
+                }
+                send_string_P((char const *)(autocorrect_data + state + 1));
+            }
+
+            if (keycode == KC_SPC) {
+                typo_buffer[0]   = KC_SPC;
+                typo_buffer_size = 1;
+                return true;
+            } else {
+                typo_buffer_size = 0;
+                return false;
+            }
+        }
+    }
+    return true;
+}